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View Full Version : Changing Tires? Think Twice! Pics to follow. Three brands of tires tested.


z51vette
02-11-2007, 01:37 AM
I Got an 07 sport pack and was looking to improve the handling and the look of the car. So I decided to get the 06 staggered 192M wheel option by purchasing two 18x9" rims for the rear. As some of you know in 07 they killed the 18" staggered wheel option and replaced it with a 19" staggered option. I didn't want to have 19s on my car and needed all season tires so I ordered it from the factory standard with 18x8" 192M wheels and 235/50 18 AS tires all around. Stock tires were Michelin Pilot HX MXM4 235/50 18 all around. Ride comfort with stock tires was OK even with the sport pack but handling is only so so. With noticeable body roll and a bit of unresponsiveness.


Since then I've tried three sets of tires on it. Reading great reviews from tirerack I ordered Kumho Ecsta ASX in 235/50 18 front and 255/45 18 rear per 06 Specs. Installed the tires and was very disappointed in them. The ride went to crap. Absolutely unbearable. Very harsh riding tire, Very noisy. Handling better but with such bad ride that becomes irrelevant. Also a weird driveline wine at certain engine speeds and gears and got Automatic Transmission shifting problems. The whine is not related to balancing. I thought it might be due to slightly shorter overall diameter of the tires. The stockers 235/50 18 Michelins are 27.5" OD (overall diameter) and 759 revolutions per mile. The Kumhos are 27.3" OD front and 27" OD rear. Could not find Revolutions per mile on this tire anywhere in the specs. The whine sounds like gear whine, short duration for a few seconds at a time and could be present at any given time and speed. Just from standstill or going 65 on the highway.

At first I thought it was the tires so I got a set of Michelin Pilot Sport AS in the same 235 front 255 rear sizes. After mounting them on the car the whine went away completely. The ride improved but still harsher than Pilot HX. A bit too harsh for my taste. Much quieter than Kumhos and possibly even quieter than stockers on the highway but not over bumps and expansion joints. Handling is fantastic. Feels like a different car. Response is immediate with absolute absence of body roll. What I hate about this tire is the width of the rear 255/45 18 tires. I don't know what Michelin was thinking but they decided to make 235/50 18 and 255/45 18 dimensionally identical. Meaning they are the same width. It looks weird on a 9" wide rim and looks too skinny in the back. Really kills the staggered look. They are both 27.2" OD and 762 revs per mile. Very close to stock (759 revs per mile). Less than 1/3 of a percent deviation from stock OD. Since the whine disappeared I thought to myself maybe it was the difference in diameters of the Kumhos 27.3" front, 27" rear or even a problem with the tires themselves.

Back to Michelin Pilot Sport AS. Unhappy mostly with the look of the rear tires and after getting a few complaints from rear seat passengers about ride quality I went on a new tire search. Now looking for identical or very close diameter front to rears and the ultimate in width rear tire. I came up with Pirelli P-Zero Nero MS in 245/45 18 front and 275/40 18 rear. Specs say these tires will work fine on 18x8 and 18x9 wheels respectively. They are 26.7", 26.6" OD and 780, 782 revolutions per mile front/rear. They are within 2% of the stock diameter. And I thought to myself a worn stock tire would be close to the diameter of these. So I got the tires. Which, mind you was not an easy thing to do. The 275/40 18 is on national back order. No one had these tires. Had to get them shipped from Pirelli directly after a few favors. Got them installed. From the rear the car looks fantastic. This is what the sport pack X3 should look like. Very meaty and mean look to it, though the tires seem to fill the wheel well a little less due to the smaller diameter. Driving impressions: The tire is supremely quiet. Quieter than Pilot Sport AS or the Stock Pilot HX tires. Comfort is better than Pilot Sport but maybe not as forgiving and Pilot HX. After all this is a Z rated tire and the stockers are H rated. Handling is great though responsiveness not as sharp as Pilot Sport AS. Possibly due to the wider 275 tire on the same 9" rim as the 255 Pilot Sport AS. On the Negative Side. The driveline/gear whine is back. Also the AT shifting problems are back. I think the speedometer is way off now by as much as 10MPH at 60. However I wasn't able to verify this. Maybe they are just so quiet that I think I'm going slower. After all 2% difference in size should yield only about 1.5 MPH difference going 60. Now I know for certain that changing tire size will cause all sorts of computer related problems even if it is only a very minor change.

Here is my dilemma. Can the computer be reprogrammed to compensate for tire size? Spoke to a few dealers they tell me, NO, only the factory can do that. Kind of hard to imagine the dealer can't reprogram for tire size. It is very simple to do even with basic hypertech programmer on almost all GM cars. Why would BMW only reserve that for the factory? If I'm not able to get the car reprogramed I will probably have to put my stock 235/50 18 Pilot HX MXM4 tires back on. That would be a shame, not to be able to keep the best tires for the car after spending all this money just because of dealer incompetency in reprogramming the ECU.

Anyone know how to reprogram the ECU for tire size?

I will post pictures of Michelin Pilot Sport AS and Pirelli P-Zero Nero On my car shortly.

dug01
02-11-2007, 07:16 AM
Go here for a nice tire size/revs per mile calclator--
http://www.1010tires.com/TireSizeCalculator.asp?action=submit

Ihave the p-zero nero M&S on my Z4 and although I never take it in the snow they are great in the rain and super on dry pavement--a vast improvement over the Bridgestoner run flats--much better ride and quiet--and good looking. Michelins are great tires but I think overpriced--Tire racks reviews and survey shows that there are better tires for the money and the P-zero's are one of them.

bobotski
02-11-2007, 12:01 PM
Interesting review. Verify that there was indeed a change in speedometer reading. BMWs I think were designed to be a few mph below the actual speed, sort of a safety buffer when targetted/radared by the cops. There was a thread here before, try searching for it.

Bobert
02-11-2007, 12:58 PM
Thanks for the review of different tires. You are spot on about ASX. I have them on my Jetta and even went up a size from 205/50/15 --> 205/55/15 hoping the taller sidewall would help the ride.. Well, they ride like absolute bricks, even with the taller sidewall. Very disappointed with them. They even get fairly good ratings at tirerack for ride comfort which I can't really understand. I'm probably going to go with one of Yokohama's passenger tires (maybe TRZ), just to get some of the ride quality back.

The MXM4 on the other hand does have pretty good ride quality on my family's X3 with standard 17" wheels. The steering response is not bad either for a grand touring all season tire. We're pretty happy with them so far, so hopefully they will work out. The MXM4 doesn't seem to have good snow performance though according to reviews, so Pirelli STR will probably better suited for trekking through the slippery stuff with X3.

mikewinebf
02-11-2007, 06:26 PM
I'm interested in seeing your photos. I hve a 2007 on the boat and unloanding in San Pedro, CA next week. I was unablet able to get the 19's and it will come with the SP's 18's
I would like the wider wheel and tire of the 2006 at the rear and am interested in your ideas for the best tire combanation. I have no idea what mine will have when it arrives, but most likely Michelins.

Ride is important but not paramont, I'm leaving a Lexus RX 330 due to its clumsy handling.

I had an X5 before that, but it was sold beceause of disasterous reliability. nearly everything failed including the transmission. But what a car to drive.

Jalli
02-11-2007, 06:33 PM
What were you driving before this? I am interested to know..

I think you might be going out of your way to solve a "problem" that is not really a problem..
BMW's with sport package are renowned for their harsh ride.. it's something that you accept at first, and then get used to ..

As you indicated above, I guess you found a tire that works well for you though so...

As for the tire/whell reprogramming, I have never heard of anyone having to do this ona BMW.. I think the computer is able to compensate for most stock wheel and tire combinations..

As for snow performance, I think that many people spend too much time worrying about this.. I have driven through light to moderate snow in my X5 with 19' and sport package with Michelin Diamaris (sp?) and not really had any problems..
Sure, I am not zooming through at 80mph, but no real problems.. Just adjust your driving habits..

z51vette
02-11-2007, 09:40 PM
What were you driving before this? I am interested to know..

I think you might be going out of your way to solve a "problem" that is not really a problem..
BMW's with sport package are renowned for their harsh ride.. it's something that you accept at first, and then get used to ..

As you indicated above, I guess you found a tire that works well for you though so...

As for the tire/whell reprogramming, I have never heard of anyone having to do this ona BMW.. I think the computer is able to compensate for most stock wheel and tire combinations..

As for snow performance, I think that many people spend too much time worrying about this.. I have driven through light to moderate snow in my X5 with 19' and sport package with Michelin Diamaris (sp?) and not really had any problems..
Sure, I am not zooming through at 80mph, but no real problems.. Just adjust your driving habits..


My other cars are C5 Corvette with Z51 autocross performance package and runflat tires, a 94 Caprice 9c1 police car with modified super hard suspension and Impala SS modified for racing. We are not talking cars with plush ride here. So when I say the ride was bad, It must be really bad. I've never felt that uncomfortable in the Vette even over potholes. So the kumhos were not tolerable at all. Really felt like driving around solid rubber wheels. Not only the ride was horrible, but the audible quality was very annoying. Pirelli P-Zero Nero on the other hand feels incredibly smooth and supple on a freshly paved highway and not bad over potholes. Plus the sound quality is much better over potholes. Where the kumhos would resonate throughout the whole car like an empty tin can, the Pirellis produce more of a low frequency thud over potholes and expansion joints.

Michelin Diamaris is an all season tire. So I'm not sure what point you are trying to make here.

d-rive
02-12-2007, 05:08 AM
I will post pictures of Michelin Pilot Sport AS and Pirelli P-Zero Nero On my car shortly.

so, where are the pictures, i am still waitting :)

simoncpw
02-12-2007, 06:54 AM
Um... interesting!

I also have a stagger set up 18x8" + 18x9", and the exact same size of Michelin Pilot Sport tires 235/50 18 + 255/45 18. But the physical dimension is NOT identical. The rear is about an inch wider (as it's should!) and looks ok to me!

What I hate about this tire is the width of the rear 255/45 18 tires. I don't know what Michelin was thinking but they decided to make 235/50 18 and 255/45 18 dimensionally identical. Meaning they are the same width. It looks weird on a 9" wide rim and looks too skinny in the back. Really kills the staggered look.

mikewinebf
02-12-2007, 08:47 AM
Great looking conversion, and I agree the rear wheels and tires do a fine job of filling out the wheel wells.

z51vette
02-12-2007, 12:19 PM
Um... interesting!

I also have a stagger set up 18x8" + 18x9", and the exact same size of Michelin Pilot Sport tires 235/50 18 + 255/45 18. But the physical dimension is NOT identical. The rear is about an inch wider (as it's should!) and looks ok to me!


Do you have Pilot Sport or Pilot Sports AS. Your post made me go to local costco and
order one 255/45 18 Pilot Sport AS tire just to measure it. If it is in fact wider than the 235 that means the 255's I got were defective.

mikewinebf
02-12-2007, 12:46 PM
I had them on my X5 with the 19' wheels, They managed snow just fine, but were leathal on ice.

simoncpw
02-13-2007, 05:02 AM
Sorry z51vette, I read your post too quickly and didn't notice the "AS".

I have the Pilot Sport. But I'm intested to know if the AS is any different in the physical dimention.

Do you have Pilot Sport or Pilot Sports AS. Your post made me go to local costco and
order one 255/45 18 Pilot Sport AS tire just to measure it. If it is in fact wider than the 235 that means the 255's I got were defective.

Nick325xiT 5spd
02-13-2007, 05:29 AM
Sorry z51vette, I read your post too quickly and didn't notice the "AS".

I have the Pilot Sport. But I'm intested to know if the AS is any different in the physical dimention.
The Pilot AS is super gooshy.

adc
02-13-2007, 09:08 AM
The Pilot AS is super gooshy.

Is this good or bad? :D

z51vette
02-14-2007, 05:01 PM
Didn't really get a chance to take some meaningful pics of the Pirelli P-Zero Nero MS because of the recent weather but here are some pics in the meantime.

I got some comparison shots for you of the Michelin Pilot Sport AS and Pirelli P-Zero Nero MS.

Pirelli P-Zero Nero MS is in the pictures with snow. Look at the width of the rear tire This is what the Sport Pac X3 should have looked like from the factory.

Look at this picture. Can you tell which one is 255/45 18 and which one is 235/50 18. The only visible difference is wider shoulder blocks on the 255 tire which is on the right. This is my main gripe with Michelin Pilot Sport AS. As you can see from the below pictures the Tire is actually stretching outward to fit on the 18x9 rear rim.

http://www.designwholesale.com/bmw/x3pics/tires/mfr.jpg

http://www.designwholesale.com/bmw/x3pics/tires/mside.jpg

http://www.designwholesale.com/bmw/x3pics/tires/mside2.jpg

http://www.designwholesale.com/bmw/x3pics/tires/mrear.jpg

http://www.designwholesale.com/bmw/x3pics/tires/mrear2.jpg

http://www.designwholesale.com/bmw/x3pics/tires/prear.jpg

http://www.designwholesale.com/bmw/x3pics/tires/prear2.jpg

http://www.designwholesale.com/bmw/x3pics/tires/pside.jpg

dug01
02-14-2007, 05:38 PM
My '07 came with 255-55-18 which are 29" diameter--isn't 235-50-18 at 27" diameter way too small??--I think the 29" on mine look small for the large wheel openings--the 27" look way too small.??
:dunno:

Bobert
02-14-2007, 06:04 PM
Dug01 I think all the rim/tire combos are within ~27.3" range. Strange yours would have 255/55/18 tire. Some were complaining that the DSC light would sometimes come on because they were running larger diameter tires. Have you noticed the light come on?

z51vette
02-14-2007, 06:16 PM
My '07 came with 255-55-18 which are 29" diameter--isn't 235-50-18 at 27" diameter way too small??--I think the 29" on mine look small for the large wheel openings--the 27" look way too small.??
:dunno:

There was no option for 255/55-18 in 07. In fact that was never available on any x3. 07 comes with three possible tire sizes. 235/55-17 standard, 235/50-18 Optional and sport pack and staggered 235/45-19 front, 255/40-19 rear. In 06 there was a staggered option of 235/50-18 front, 255/45-18 rear which is what I tried to duplicate on my 07.

255/55-18 is an X5 tire. If you actually have this tire on your car please send me a pic. I would love to see 29" tires on the X3. I agree with you that BMW's made a bad decision to put 27" tires on X3. The should have been at least 28". 29" though would be too tall on the x3.

Please send a pic of your car.

Bobert
02-14-2007, 06:26 PM
dug01, post a photo here on the forum your 29" tire on X3, because I would like to see this as well.

dug01
02-15-2007, 09:04 AM
dug01, post a photo here on the forum your 29" tire on X3, because I would like to see this as well.

Sorry--My Bad-:yikes: -I went to tire racks web site and instead of entering X3 I entered X5 and that is how I got the 255-55 size--I just went out to the garage (It is 1 degree here) and looked and you are right it is 235-50-18--which is just over 27" --I will spank myself now-- :spank:

robert doyle
01-27-2008, 04:54 AM
very helpful and informative. thanks for your time and research.
bob