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E85 / E86 Z4 (2003-2008)
E85 Z4 Roadster, E86 Z4 Coupe, E85 Z4 M Roadster, and E86 Z4 M Coupe talk with our BMW gurus here.

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  #1  
Old 07-12-2015, 09:51 AM
lmacmil lmacmil is offline
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Anyone downgrade their wheels from 18" to 17"?

I decided to start a new thread to follow up on my discovery that my 3.0Si has the wrong size tires all the way around and mismatched rears to boot.

I've got the staggered 18" V-spoke 294 wheels with lots of curb rash on every wheel. I also have the M-sport suspension according to the VIN check I did. Since this is a summer/weekend car, I don't want to spend a lot on replacement tires. Given the annual mileage I am likely to put on, the tires will be ready for replacement by age long before they are worn out. Which brings me to my question.

What would be the downsides of converting to OEM size 17" wheels and tires. I assume the speedometer calibration might be off a little. I'm sure I'd give up some handling performance at the 8/10ths level but that isn't a concern for me. The ride might improve slightly due to the higher profile. The other upside, though only cosmetic, would be getting rid of the beat up 18" wheels. The overall cost would be higher this time but if I have to replace the tires in 6 years of so, it would just about be breakeven.

I'm new to the Z4 world so I'm hoping for some insight. Thanks.
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  #2  
Old 07-12-2015, 10:13 AM
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ebruder ebruder is offline
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I exchange wheels/tires every winter/summer on my Z4MCoupe. I put on skinnier 17" wheels and snow tires in October, and then change back in April.

The speedo calibration is off by a little, but only a little because I get higher profile (and narrower) 17" snow tires.

The handling definitely suffers on dry roads, but that is probably more from the tire compound than the size. With the Borbeck (sp?) wheels that I got from Tire Rack, I had to use 2 spacers on the rear. Tire Rack spec'd these, and they worked perfectly.

I would hesitate in down sizing if snow tires are not going on. Propoer wheel/tire size and quality are so valuable in handling.

EB
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  #3  
Old 07-12-2015, 10:41 AM
Twixboy Twixboy is offline
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As a summer/weekend car you must have purchased it for one of 2 reasons: performance or looks. Since you said you don't care about performance I can only imagine you are the type of owner who picked the Z4 because it looks good. I recently considered downsizing from 18's to 17's to save money, but after looking at 17's on another Z4 I decided I couldn't do it. Ignorance is bliss. If you already have 17's then it's fine because that's what you have and it looks good to you. But if you already have 18's then you'll notice a drastic difference going down to 17's. It's like dumping Scarlett Johansson for Amy Poehler. Amy's not ugly, but she doesn't compare to Scarlett.
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Old 07-12-2015, 11:04 AM
lmacmil lmacmil is offline
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Quote:
Originally Posted by Twixboy View Post
As a summer/weekend car you must have purchased it for one of 2 reasons: performance or looks. Since you said you don't care about performance I can only imagine you are the type of owner who picked the Z4 because it looks good...It's like dumping Scarlett Johansson for Amy Poehler. Amy's not ugly, but she doesn't compare to Scarlett.
Like your analogy!

I didn't say I didn't care about performance. I said I doubt I'd notice the performance difference between 17" and 18" tires because I don't drive at 8/10s (at least not very often). After doing some research, I find that the 17" and 18" tires are the same diameter within .10" (so my concern about speedo/odo calibration is moot.)

So my dilemma is do I get the 18" tires and live with the less than perfect rims or do I get a 17" wheel and tire package, enjoy shiny new wheels and give up a little in the performance department. I'd say it's more a choice between Scarlett and say, Rashida Jones, than between Scarlett and Amy.
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Old 07-12-2015, 11:39 AM
fatcatsailor fatcatsailor is offline
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If you want to get buy a little less expensive, check out what I did (not intentionally). I got rid of run flats, but I did a lot of research and decided to buy BF Goodrich Gforce sport comp 2. I can tell you these are awesome tires in an 18 inch wheel. VMR 710 wheels in 18 inch and gunmetal. Totally changed the car for not much difference in price as 17 inch wheels and tires are getting harder to come by and less choices to pick from. These comp2 tires are reasonable and I love everything about them even the looks and tread. I am not a cheep ass but what a tire and price.

No way would I ever go back to a 17 inch wheel
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  #6  
Old 07-12-2015, 12:32 PM
TennesseeZ4 TennesseeZ4 is offline
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New 294's

If getting new wheels is an option, why not get some new 294's? Or take them and get them refinished? We have had a couple of wheels from my bride's E350 redone, and you cannot tell them from new. Might make more sense to approach it from that direction. Or go for some aftermarket wheels in the proper size.
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Old 07-12-2015, 12:33 PM
kalali kalali is offline
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I'm not sure how you're doing the math. If you already have 18" wheels, I don't see how it would be cheaper to get a set of new wheels and tires vs. buying a set of new tires unless you go with real crappy quality. That aside, I can assure you from experience that the choice of tires makes a lot more significant difference in performance than the size of the wheels. If it were me, I'd keep the wheels - may be get them refreshed, and get a set of quality summer tires in the correct size.
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Old 07-12-2015, 12:48 PM
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enzed4 enzed4 is offline
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My Z4 came with 17" wheels - I had no choice as the dealer had given the 18" M-sport wheels on the Z4 to another customer. They're shod with Pirelli P7's and I can't say I've had any problems with them, although I don't treat them too harshly. As for the size, it would be nice to have the spec 18" wheels, but I'm not losing any sleep over it. I think the lowered suspension helps the wheels 'fill' the gap nicely.

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Old 07-12-2015, 12:50 PM
lmacmil lmacmil is offline
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Quote:
Originally Posted by kalali View Post
If you already have 18" wheels, I don't see how it would be cheaper to get a set of new wheels and tires vs. buying a set of new tires unless you go with real crappy quality.
It wouldn't be and I didn't say it would. It would be more now but the savings on the 17" tires would partially offset the cost of the new wheels. And when I needed tires again in a few years, the same savings would be there.

I am now leaning towards keeping the 18" wheels (where does one get them refreshed?). I may just do the rear tires to start with so I can spread out the cost. Since the rear tires are mismatched in both size and style, they need to be replaced right away, IMO.
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Last edited by lmacmil; 07-12-2015 at 12:52 PM.
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  #10  
Old 07-12-2015, 12:56 PM
lmacmil lmacmil is offline
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Quote:
Originally Posted by TennesseeZ4 View Post
If getting new wheels is an option, why not get some new 294's? Or take them and get them refinished?
I'll look into getting them refinished. No way I would spend $500+ each on new wheels.
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Old 07-12-2015, 01:55 PM
Twixboy Twixboy is offline
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Quote:
Originally Posted by lmacmil View Post
Like your analogy!

I didn't say I didn't care about performance. I said I doubt I'd notice the performance difference between 17" and 18" tires because I don't drive at 8/10s (at least not very often). After doing some research, I find that the 17" and 18" tires are the same diameter within .10" (so my concern about speedo/odo calibration is moot.)

So my dilemma is do I get the 18" tires and live with the less than perfect rims or do I get a 17" wheel and tire package, enjoy shiny new wheels and give up a little in the performance department. I'd say it's more a choice between Scarlett and say, Rashida Jones, than between Scarlett and Amy.
Right, the 17" rim is smaller but it has meatier tires which makes it the same overall size. That's required for the odometer to work properly no matter if it's a Z4 base or a Z4 with sports package. So the smaller the rim, the more comfortable the ride. Yeah, I don't think you'd notice the performance difference for regular driving around town. Wheel refinishing varies from shop to shop, but around here it ranges from $75-200/wheel. $100 is average for a couple small curb rashes. It should be cheaper if you live in a lower cost of living state.

Quote:
Originally Posted by enzed4 View Post
My Z4 came with 17" wheels - I had no choice as the dealer had given the 18" M-sport wheels on the Z4 to another customer. They're shod with Pirelli P7's and I can't say I've had any problems with them, although I don't treat them too harshly. As for the size, it would be nice to have the spec 18" wheels, but I'm not losing any sleep over it. I think the lowered suspension helps the wheels 'fill' the gap nicely.

Enzed, you are right - those wheels look nice in the picture especially with your drop. But when I looked at my 18's sitting next to another Z4 with the same 17's that you have, I couldn't help but notice how much of a difference the 18's made in person. Granted, the other Z4 wasn't lowered and had huge wheel gaps compared to mine which has the 15mm lower M sport suspension.
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Old 07-12-2015, 02:16 PM
pokeybritches pokeybritches is offline
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You may actually notice a performance increase by going to 17" wheels versus 18" wheels, assuming there is unsprung weight savings. The challenge will be finding a set of 17" wheels that are at least 8.5" wide to fit the 255 width rear tires. Most stick with 18's because of the performance tire choices. If you think the tires may age before they wear out, you can put on some stickier max performance summer tires on 18's, which may not be available on the 17's.

If you're on a budget, I would get the OEM wheels refinished instead of buying new ones.
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Old 07-12-2015, 09:00 PM
impreza276 impreza276 is offline
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Apart from the unsprung weight savings there is an extra 0.5 inches of tire cushioning which should make a very noticeable difference.
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Old 07-13-2015, 01:40 AM
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dc_wright dc_wright is online now
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Quote:
Originally Posted by lmacmil View Post
It wouldn't be and I didn't say it would. It would be more now but the savings on the 17" tires would partially offset the cost of the new wheels. And when I needed tires again in a few years, the same savings would be there.

I am now leaning towards keeping the 18" wheels (where does one get them refreshed?). I may just do the rear tires to start with so I can spread out the cost. Since the rear tires are mismatched in both size and style, they need to be replaced right away, IMO.
Just do a Google search on "powder coating" there in South Bend. You'll likely find a half dozen or more places that do wheels.
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Old 07-14-2015, 06:47 AM
lmacmil lmacmil is offline
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Just to wrap up the thread, I decided to keep my 18" wheels and went with the Conti ExtremeContact DW. They are summer tires which is fine because the car won't be driven in the winter. Definitely sharpened up the steering response vs the old, incorrect size all-seasons.

Thanks for all the replies.
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