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Seek to understand,^Value
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Discussion Starter #1 (Edited)
May we hone the B A S I C S of choosing tires for your BMW E39?
This thread is NOT intended to be a discussion about any particular tire!

We all know there are zillions of highly opinionated threads, filled with mostly unsubstantiated inconsistently anecdotal Bro Science subjective evidence, all purporting to answer, ad infinitum, the timeless question of what replacement tires to buy for your beloved BMW E39.

This thread, I hope, is different in that it attempts to hone a logically and statistically valid basic approach to the tire selection decision. Let's discuss the basics of how to select tires; but let's stay away from the particulars of any one particular tire brand or model (plenty of threads cover that!).

As is my bent, I will embarrass myself by intimating my own personal logical tire selection choice - and let others hone this process for me - with the hope that we can point others to this thread - who need to make a tire-selection choice in the future.

EDIT: As ideas come in, I'll incorporate them into this post for the convenience of those coming after us.
A basic approach to a logical selection of replacement tires for your E39:

  1. - Size (the same size you're replacing is a good start)
  2. - Tire Rack reviews (as discussed later in this thread)
  3. - UTQG Traction, wet pavement, straight line (AA only)
  4. - UTQG Temperature, i.e., top speed under load (A only)
  5. - UTQG Treadwear (useful when comparing two otherwise equal tires, higher is better, assuming all else is equal)
  6. - Manufacturing date (all things equal, buy the newer tire over the older)
  7. - Total cost (all things equal, the tie breaker is the lower installed & balanced price)
  8. Notes:
  • I ignore the manufacturer's "speed symbol" as it is not vetted by anyone but the marketing department.
  • For a sedan, in the USA, the load index is also not generally a key determining factor, so I just check that it's at least the minimum specified by the manufacturer.
  • In general, one must be careful with tire-rack user evaluations because you must separate the wheat from the chaff manually. See later posts for algorithms to garner useful data out of the tire-rack reviews.
  • The "Bro Science" says that the higher the treadwear number, the lower the traction; but since they're measured objectively separately, there's no reason to make that (highly incorrect) assumption of the inverse proportionality of the two factors.
A secondary basic question could be WHERE to best buy tires:
- Tire Rack ?
- Costco ?
- America's Tire Stores ?
- Sears ?
- Local tire shop (e.g., Wheelworks, Goodyear, Big-O, GoodWrench, Firestone, etc.)
- ?where else is suggested?

 

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America's Tire Stores, if you like your nice wheels abused.

Tire selection is, I'm afraid, like mate selection: LOTS of emotion involved.
 

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Good thread.
Also, some folks changed their rims with bigger ones, so having the right aspect ratio is important. Here is a calculator, so the odometer will read close to the correct spec.
And just to touch on the rim subject, some people always ask if the rim will fit. Here are the BMW wheel specs (in case one wants to go aftermarket).
Just to keep this in a consolidated thread.
Thanks Donna.
 

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Seek to understand,^Value
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Discussion Starter #4 (Edited)
LOTS of emotion involved.
Hi Edjack,

For the first time (I think), I'm going to disagree with you.

Lot's of emotion is often involved - but - it doesn't have to be involved.

PT Barnum was right. The less people know about something important (e.g., tires, brakes, motor oils, coolants, etc.), the more they substitute subjective emotion and Bro Science for objective logic and tested statistically valid facts.

I've always made a case for logical decisions, for example:

I see no reason why outlining a basic selection process for tires, removing anecdotal evidence and relying on statistically valid tests, would be any different.

Buying tires any other way is simply playing into the hands of the marketing guys!
 

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Good thread.
Also, some folks changed their rims with bigger ones...
Can we safely assume you are using slang terminology for a "wheel," and not actually talking about just changing the size of the rim on it? Changing a rim will affect the width of an assembled wheel, though not the diameter. Although, widening the wheel by installing a larger (deeper) rim would subsequently affect the tire size that could be put on it.
 

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This is a very subjective process. Quantifying criteria for tire selection is tricky because much of the "data" is not an entirely accurate reflection of the operational context (like EPA gas mileage figures). Is a treadwear number established on a test machine (which is quantifiable & repeatable) the same as what occurs in real life? Not entirely. Consequently, I tend to ignore these mfg specs because they tend to lack real world credibility. Just like I ignore Car & Driver track times because I do not track my cars. I also don't really care about tire speed ratings (V, S, etc.) as my driving is well below 100 mph. I think manufacturing date is important but you have little control over that. Has anyone ever refused to buy a tire based on mfg date? If you buy a popular tire, it should not sit on the shelf for many years. Anyway, here's my $0.02 on my process:

First, I ensure that the brand/model I want to consider is actually available in my required size.

Then (contrary to your approach) I review the Tire Rack surveys. I typically place greater credence on real life feedback than a mfg spec and I find this an excellent source of anecdotal data depending upon the usage mileage accumulated for that specific tire. Higher mileage = greater statistical significance. While there is always a broad variance of opinion, a few million miles of useage tends to average out the extremes. I also check into specific model feedback as a tire on a FWD car is not the same as the same tire on a RWD car. Then depending on which car (I own an e39, Civic & an Explorer) I am buying for, I prioritize the various criteria that are most important for me:

dry handling & braking, wet handling & braking, hydroplane resistance, ride
noise, treadlife, snow performance if applicable, etc.

Only then do I consider price. If a tire is really, really good, I am willing to pay more. However, once you establish your final pool of candidates, I find that most tires in the pool are relatively similar WRT performance. Hence, I try to find the tire that offers the best value.

Then I do an internet search for best price. I have a local tire dealer that offers to beat any Internet price so i usually just go there and have them match the best online price I can find. They mount, balance and align for $90. Not exactly a science but it works for me.


BTW, I am currently buying a set of tires for the Explorer, need 4 new summer tires for the Civic (it's on snows) and could use 4 new snows for the e39 (3/16 tread left). So I have been applying my "process" a lot! I am looking into a "package" deal! :rofl:
 

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Can we safely assume you are using slang terminology for a "wheel," and not actually talking about just changing the size of the rim on it? Changing a rim will affect the width of an assembled wheel, though not the diameter. Although, widening the wheel by installing a larger (deeper) rim would subsequently affect the tire size that could be put on it.
Semantics. You know and nailed it (what I was talking about).
 

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Semantics.
Perhaps, although technically these words are not interchangeable and I won't deny being pedantic about it, as use of the word "rims" when discussing "wheels" is one of my pet peeves. That said, I think most everyone would agree that using the correct terminology is important when trying to put together an accurate summary and/or KB article that will hopefully one day make its way to the E39 Wiki page.

Speaking of which, has anyone seen the E46 Wiki? It has literally triple the amount of data/info as the one for E39s...
 

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Speaking of which, has anyone seen the E46 Wiki? It has literally triple the amount of data/info as the one for E39s...
That's because there are three times as many e46s around. And if you go to the e60 site, there is ZERO information, DIYs, etc. I think each site is a reflection of the drivers of those vehicles.
 

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Seek to understand,^Value
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Discussion Starter #10 (Edited)
This is a very subjective process.
But, it doesn't necessarily have to be highly subjective. Surely we can come up with a basic algorithm.

Is a treadwear number established on a test machine (which is quantifiable & repeatable) the same as what occurs in real life?
No. But that number isn't based merely on a machine.

For the Uniform Tire Quality Grading (UTQG) treadwear test results, they actually pay four sets of drivers to drive 11,520km in 640km repetitive loops in San Angelo, Texas, stopping every 1,280km to measure treadwear under these "perfect" outdoor and road conditions.

The only reason we don't get the same number of miles is we don't drive in perfect conditions.

Every manufacturer must use the same test, same test track, same conditions, etc. (AFAIK).
Note: I'll need to look that complete test process & rules & regulations up to be doubly sure.

Let's see if others agree to keep the UTQG grading factors in the final decision tree.

I also don't really care about tire speed ratings (V, S, etc.) as my driving is well below 100 mph.
I agree with you here. These S, H, V, Z, etc. ratings are pure M A R K E T I N G gimmicks. PT Barnum would be proud how much credence the average tire buyer gives to these essentially meaningless (from a test standpoint) numbers.

Nobody vets them. They are only rated by the manufacturer. Therefore, they are suspect from the start because they're based on a flawed model.

Let's see if others agree or disagree with us for the final decision tree.

There is no standard test that they all have to follow
Not true. All the UTQG tests are standardized and repeatable. Their major flaw is they're run under perfect conditions; but that beats anything else we have so far.

Hopefully, someone will suggest further decision tree factors to consider.

manufacturing date is important but you have little control over that.
Agreed. It's mainly used by me to pick through the Costco lot for the latest batch of four! :)

Let's see what others think about that.

I ensure that the brand/model I want to consider is actually available in my required size.
Good point. This begs a question of our starting comparison point.

What is the OEM brand and model for the various BMW E39s?

The specs on those OEM tires should be our starting point, I would think. Do you?

I review the Tire Rack surveys.
We should add this to the decision tree IF others agree (as my opinion on tire rack reviews isn't the only opinion out there).

feedback as a tire on a FWD car is not the same as the same tire on a RWD car.
Good point. We should cover that in the decision tree if others agree.

I prioritize ... dry handling & braking, wet handling & braking, hydroplane resistance, ride, noise, treadlife, snow performance if applicable, etc.
In that order?

If others agree, we should add that prioritization factor set to the decision tree.

most tires in the pool are relatively similar WRT performance. Hence, I try to find the tire that offers the best value.
Excellent observation!

have them match the best online price I can find.
I forgot about that trick. It worked for me once, accidentally.

The Goodyear shop matches Tire Rack prices. So that should DEFINITELY be added to the cost part of our tree as you need the tires mounted and balanced somewhere no matter where you buy 'em.

Let's see what algorithms others use to select E39 tires and then summarize it all up for others to use as a reference.


EDIT: I looked it up:
"Treadwear grades are tested under controlled conditions using four vehicles fitted with test tyres that run in convoy. The vehicles repeatedly run a specified 640 kilometre road course for a total of 11,520 kilometres. Tread depths are measured every 1,280 kilometres and the measurements for each vehicle are averaged to give a projected wear-out life."

 

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I tend to think that the UTQG testing has limited value. While I'm not a tire engineer but I do work for the Government as an engineer and we test a lot of "stuff" in many different ways. As such, I am very aware of the limitations of testing and the conclusions that can be drawn from testing. While those UTQG tests may be "controlled", the level of control is very limited outside of the lab and the conditions are far from "perfect". Variables exist and they are exactly that, variable. Any test is reproducible. However, if the results are not reproducible, then either the test has limitations and/or the product attribute defies consistent quantification. Many times, a flawed test process is the only way to properly evaluate a particular product. However, I think the evaluation of tires, in general, and the UTQG test process, in particular, are more subjecticve than objective.

Here is what Tire Rack says about the UTQG Treadwear grades:

"The problem with UTQG Treadwear Grades is that they are open to some interpretation on the part of the tire manufacturer because they are assigned after the tire has only experienced a little treadwear as it runs the 7,200 miles. This means that the tire manufacturers need to extrapolate their raw wear data when they are assigning Treadwear Grades, and that their grades can to some extent reflect how conservative or optimistic their marketing department is. Typically, comparing the Treadwear Grades of tire lines within a single brand is somewhat helpful, while attempting to compare the grades between different brands is not as helpful."
Any time marketing gets to participate in extrapolating test results means the process is more subjective than objective.

The traction grade testing process is also somewhat suspect:
"UTQG Traction Grades are based on the tire's straight line wet coefficient of traction as the tire skids across the specified test surfaces." and "Since this test evaluates a sliding tire at a constant 40 mph, it places more emphasis on the tire's tread compound and less emphasis on its tread design."
Tire traction is much more than simple coefficient of friction and is a function of many things. Hence, a test that evaluates a single attribute is not telling an accurate story of "traction".

And lastly, he who conducts the test has the most influence on what those testing results can say:
"When looking at UTQG ratings it is important to realize that the Department of Transportation does not conduct the tests. The grades are assigned by the tire manufacturers based on their test results or those conducted by an independent testing company they have hired."
I've seen how this happens all too often. This is equivalent to letting the wolf guard the sheep.

While your objective is admirable, I guess all I am saying is that most decision making cannot be defined into straightforward logical process because everyone prioritizes and measures things differently.
 

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I've bought tires from the local Americastire store a few times and I like them. They always match Tirerack's out of the door price, i.e. including shipping and ~$25-$35 per tire mounting fee. What you get from Americastire is free rotation and balancing every 5k mi, which you can't get from tirerack. You can call up your local Americastire over the phone and they'll match the final price. If they don't have the tires you're looking for in stock, they'll order them from their warehouse.
Sometimes I see some superlow sales prices on really good tires in tirerack (say $80 for brand name tires) and Americastire just couldn't match these sale prices, then I just order them from tirerack.
Since my car hardly sees snow or experiences freezing condition, I prefer summer tires only because of the superior traction in dry and wet. However they tend to wear out quicker than the all season.
 

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Seek to understand,^Value
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Discussion Starter #13
Based on a thread today about long-life E39 tires:
- Tyres that last for 530i

I made the following relevant comment which I will try to expand upon afterward:

I realize this is probably anathema to the 'connoisseurs' here but all USA passenger tires must be graded for traction, tread wear and speed (aka temperature).

So, here's how I buy tires (but that's just little ole' me):
- How to logically and unemotionally choose tires (1)

BTW, even if you don't subscribe to the KISS dogma that I do, you should still KNOW all that information in that thread; then you simply ADD all the crud that goes on top of the selection of tires decision. And that additional information is not only immense, but, scientifically impossible to verify for the most part. Which is why I call it crud. YMMV.

Moving forward, and looking in the bestlinks, I find the following related assemblage:

Since I already (think I) know how to choose tires (simply by five well-measured factors), I'll leave it to the reader to attempt to organize those threads into something more cohesive.

Here are my criteria (as explained in the referenced thread), in order of importance (Notice all of these are scientifically measured and validated by numerous agencies and comparable across brands as much as anything is):

  1. Size
    • For example, Pwww/hhRdd
    • Where the "P" is for passenger tire
    • The "www" is the width of the tread in millimeters
    • The "hh" is the height of the sidewall in percentage of width
    • The "R" is for radial tires
    • The "dd" is the nominal diameter of the rim, in inches (go figure they'd use inches and millimeters interchangeably)
  2. Traction
    • Wet pavement, straight line (buy AA only)
  3. Speed (aka the government "Temperature" number)
    • Ignore the ubiquitous M A R K E T I N G "speed rating", which is not tested by anyone other than the manufacturer
      • Besides, that S, H, V, Z, etc. "speed rating" is, at best, redundant.
  4. Total cost (installed)
    • Cost includes balancing, stems, & the mandatory EPA impact fee assessment (which is often as high as $5/tire in California)
  5. Treadwear
    • Treadwear range is so consistent, among equivalent tires, that wear is actually lower than price in selection importance to me, only practically mattering as a tie breaker.
    • Note: A lot of people (mostly full of horseradish) assume higher traction means lower treadwear. It's just not the case. It's the case sometimes. And it's not in others. Just look at the tested and proven numbers. We're not talking racing (where tire wear and traction are absolutely nothing like passenger tires).
  6. Oh, and, I insist on going through the lot and picking out a complete set with the latest date code!
    • I don't buy ANY tire greater than about a year old!
 

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Discussion Starter #14 (Edited)
Just to keep this in a consolidated thread
Aw, I didn't really want to to this (because I already 'think' I know how to buy tires), but, the maternal instinct in me got to thinking I should update the bestlinks with this information while it's still fresh so we can point the next person to the better updated links.

So, (laboriously) clicking on all the references in this thread, and organizing them into a keyword-rich sentence, how does this look to point newbies in the right direction in the future (EDIT: Expanded to include both wheels & tires):

- Choosing the right BMW tire size (1) (2) & tyre circumference, diameter, offset, & clearance calculators (1) (2) (3) (4) (5) & a torque conversion calculator (1) & how to logically choose tires by the numbers (1) (2) & where to buy your tires in the USA (0) (1) (2) (3) (4) (5) (6) & tire plant codes (1) (2) (3) & tire safety (1) & recommended tire pressures (1) (2) (3) & the claimed benefits of nitrogen gas (1) (2) & tire terminology (1) (2) & wheel terminology (1) & BMW wheel specs (1) & BMW & replica wheel styles (1) (2) (3) (4) & the difference between cast vs forged wheels (1) & where to find the wheel markings for proper match mounting (1) & the best products for cleaning wheels (1)
 

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Kudos to bb for always endeavoring to increase the knowledge base, but on this particular matter, I personally only have a couple of considerations.

#1 is the brand. There are some tried and true ones out there, and I was pleased to find that a brand I hold in high regard to be common equipment on these cars. I feel that alone makes a statement. After doing some research, I most likely would have purchased for my e39 the very tires it came with.

#2 Speed rating. Living in SoCal, exceeding 100mph on some of these freeways is not uncommon. East bound 8 to El Centro gives one the opportunity to find out what they, and their ride are made of, and while I'm not advocating this type of behavior for everyone, I know I want the finest contact patch available, no matter what kind of car I'm driving.

That doesn't mean I won't study every inch of information this thread yields :D
 

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Discussion Starter #16 (Edited)
I most likely would have purchased for my e39 the very tires it came with
Since many buy E39s used, do we have a lookup table for the OEM tires (brand and size)?

Speed rating. Living in SoCal, exceeding 100mph on some of these freeways is not uncommon.
I think everyone exceeds the 100mph speed at some point in their lives. My E39's highest speed, as measured on my GPS anyway, is 113mph (I'll snap a picture for you if you like; but that was when I lent the car to a friend in return for a favor. (He didn't know I had reset all the saved data beforehand ... heh heh ... sneaky me.).

The point is that the "temperature" grading "is" a speed rating. For a variety of reasons, the government didn't call it a speed rating but the temperature from the double flexing every revolution undissipated at speed is what blows tires.

My only point on the manufacturer's speed ratings is that there is no way to tell if they're bogus. And, if anyone knows me, (I used to be in software marketing, you know), you can't believe everything the manufacturer says.

Certainly it's harder to compare tires when the tester is biased and different.

That's why I give more credibility to the tested temperature (i.e., speed) rating. That's all.

EDIT: Attached a picture of the GPS 113mph speed (flare is additional).
 

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But, it doesn't necessarily have to be highly subjective. Surely we can come up with a basic algorithm.
Bluebee, a lot of the emotion or subjectivity comes from the weight the buyer assigns to the different characteristics. For example, the trade-off of sidewall stiffness for handling vs. more flex for ride comfort. Road noise threshold may be higher for some drivers than for others. Some drivers may emphasize dry over wet traction ratings because they like to drive aggressively in the dry, but cautiously in the rain.

I do like the idea of trying to establish some sort measurable standards in each of these categories to make sure our decision is based on accurate information, but trying to take all subjectivity out of the process is a futile endeavor. Hell, just owning one of these high-maintenance machines is hardly justifiable by objective criteria. It's an emotional experience at its core for me.
 

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Let's discuss the basics of how to select tires; but let's stay away from the particulars of any one particular tire brand or model (plenty of threads cover that!).
Lots of variables as mentioned above so each persons decision tree will necessarily be different.

Assuming in my case:

1. I want to replicate what the BMW engineers chose for my car (a series of compromised decisions already) 17" = 235/45/17 size
2. I want a UTQG in the 300s at least (less than 100 = R compound like on my track cars, over 400 = rides like bricks)
3. I want a brand that I've used and tested before = (insert what you've had good luck with or know will work after 25+ years of driving)
4. I want an all-season with good wet performance (cars sees more rain and dry than snow)
5. I don't want shop to rotate & balance every 5K+ (they typically don't torque to 75 ft lb nor care if they over torque and stretch the lug bolts)

=

E39 has 17" rims and came with all seasons = buy all seasons in BMW rec'd size 235/45/17 to not mess up DSC, mileage, ABS
E30 325ix has 15" rims and came with all seasons = buy all seasons in BMW rec'd size 205/55/15
Suburban has 16" rims and came with all seasons = buy all seasons in GMC rec'd size 265/70/16


Winter tires, take the same approach.

Don't have time to go to the store (your time is better spent on something else) = order from tirerack, deliver to tirevan.net, work on cars, house, hobbies while Tirevan does the work in your driveway / work garage / at your work, etc...

Don't live where tirevan.net operates? = have local shop price-match tirerack or order for home delivery and use friends machine.

Your decision tree is going to vary wildly depending on people's intended application (DE/HPDE/Driving School, street only, winter, summer, towing, etc...) access to home services, access to friends with garages or equipment or where they may actually work (shop has equipment).

Good luck with this one BB. :)

ps: I don't think the buying decision has to be emotional. I sample friends experience (PCA, BMWCCA, NASA, etc...) driving similar cars for similar applications as mine (track only, towing, street daily driver duty, some track/mostly street), look at their results and then research online. Application may limit your options as well (far fewer winter tires than all seasons)..
 

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Discussion Starter #20
order from tirerack, deliver to tirevan.net... Tirevan does the work in your driveway
I hadn't known about Tirevan. Called them just now 877-847-3826.

They are only in the Washington DC & Philadelphia area. They balance on the truck. They don't ship tires though. So, they're not a replacement for TireRack.

Don't live where tirevan.net operates? = have local shop price-match tirerack or order for home delivery
I found out that TireRack forces all it's local installers to honor the TireRack price if you bring a receipt (or other proof) that you bought the tires from TireRack.

Also, I found out that some shops (perhaps most?) will match prices with Tire Rack if you bring a printout of the recent price.

The only problem I have with TireRack is the shipping is horrendously high, about $60 per set of four, if I remember correctly. This is way more than the 10% sales tax you would pay at a local shop. However, they do ship directly to the shop of your choice - so - you don't have to schlepp them about yourself. Also, shipping to California is from their Nevada warehouse, which takes only one day to get to the Silicon Valley (while you only pay for 5-day shipping); so that's another plus.

What I recommend, algorithmically, is to PRINT TireRack prices, and then go to the local shop to see if they'll match what's on your printout.

Example:
- TireRack set of four tires = $400 + $60 shipping + $100 install/balancing/stem/disposal/%tirerack-extortion = $560
- Printout set of four tires = $400 + $40 tax + $100 install/balancing/stem/disposal = $540

Twenty dollars isn't all that much - but - why give it to the California government who is just going to waste it anyway. (I implore people not to brazenly feed the drunken behemoth, as the power to tax involves the power to destroy.)

Your decision tree is going to vary wildly depending on people's intended application
There are a good selection of tires listed in this unlikely thread today:
- E39 (1997 - 2003) > road noise

And, this unemotional algorithm was also proposed:
I define "best" as the UTQG AA in traction and A in temperature (i.e., speed), with the treadwear number being the tie breaker.

That way, it's really simple to choose tires!

Then, to choose installers, I 'print' the Tire Rack prices you'd pay for installation, and choose the cheapest of those ... (balancing, rubber stems, disposal fee, % tirerack kickback, etc.).

Notice I don't 'pay' for that up front. I just 'print' it out. It turns out that all companies that show up in the tire rack installation search agree, ahead of time, contractually, with TireRack, to honor those prices if you prove you bought your tires from TireRack.

So, I just bring that printout and the tires to wherever is cheapest at the moment for installation - and voila!, I'm tired!
 
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