What is the widest tire anyone here has mounted on the stock 17" x 8 wheels? I know that 265x40-17" are just about the same diameter as the 235x45-17", but they recommend 17 x 9 wheels or wider for the 265s. I figure that the 265s would fill my rear wheel wells better, without having to get a new set of 18 or larger wheels. I notice that some suv's run this width on just 8" wide wheels. What is the downside of doing this?

If your goal is to fill the wheel wells better, wider tires isn't the way to go because the rims will still look so inset.

I have 265s on 9.5" rears and I'm told I'm ok putting a 275 but that's it. From everything I've heard I'd never put a 265 on an 8" rim. 265mm = 10.4" so that's a lot of overhang on an 8" rim. I haven't even heard of anyone doing a 255!

I have a gs430 with 255/40/17's on my rear stock 17x8's. Almost no overhang, and almost imperceptible wheel well filling. I am going to try to take them back and see if I can get 265/40's. I bought H-rated DiscountTire Rage tires to tear up at the drag strip, and I wanted more BMW-like overhang than I got. Back in the days 5-10 years ago, on 3's and 5's, BMW put a tire on 2 sizes too wide and tall for the wheels, and it had a powerful look to it, like tires that wide were needed to control the power.

But the stock 17x8s are holding my 255/40/17's in the rear with no problems. This comes unfortunately, because I wanted them to look different. They are 1.16% faster spinning, contributing to 1700 more miles per 10000 miles driven. 255/45 will also fit and save you mileage on the odometer, but the 255/40's lower my gear ratio a bit, and I'm anxious to see what it will do on the track. I am only going to keep them on during drag season, which ends 11/01 here in Ohio.

Hey rocket,

thanks for the detailed info.

mind analyze the diff(if any) on the odometer or any other factor, of choosing 245/40/18+275/35/18, versus 245/40+285/35

based on my calculation, the 1st combo is the closest to the original 225/55/16.

thanks a lot.

william

[QUOTE]Originally posted by gs4will
[B]Hey rocket,

thanks for the detailed info.

mind analyze the diff(if any) on the odometer or any other factor, of choosing 245/40/18+275/35/18, versus 245/40+285/35

based on my calculation, the 1st combo is the closest to the original 225/55/16.


http://www.powerdog.com/tiresize.cgi

You can find the info you need on this site

TM,

thanks for the info.

Rocketslug,

Will the 255/4017 also fit on the front without rubbing? What size tire will you switch back to after the season?

I would keep the 235/45x17 on front and put 265/40x17 on back, if I could. It is too bad you can't order 17" factory chromes in 9 or 9 1/2" widths. If that was possible I would order 2 and leave the front and spare as is.

RocketSlug's information was great. The difference in 10,000 miles is only 170 miles not 1700 at 1.7% as stated. Those darn decimals!!

Any pics RS?

TIA

Sorry, I haven't replied in so long. . .I will dust off the digital camera and get a photo on here of what it looks like.
As for 255/40/17 on the fronts. . .There is almost NO overhang, and I believe it indeed would work on the front wheels. In fact, that's what I will probably eventually do when I need new tires. I don't think I can measure the overhang, it is under 0.5 inch or less.

17x8 wheels are plenty big and there are a lot of tires that can fit without modifying odometer/speedometer. The perfect replacement tire to match stock diameter is 265/40/17, which is what I should of put back there.

Another note on my 255/40/17's, they almost never slip on a launch, but when they do, it seems like the VSC and Traction Control are more aggressive on the 2001 gs430. I lit them up last night on an offramp. . .can't wait to see the patch.

I drag with them tomorrow.

Rocketslug,

Any pics of the 255/40-17 setup on frt and back would be appreciated.

Thanks,

Ok,

Sorry for the wait, but it was too dark when I got back from the track for photos. The 255/40/17s did what I wanted them to do, I had no slips off the line, and I feel a lot better about doing burnouts on $250 tires instead of $500 ones.

Ok, to clear up confusion, I have stock 235/45/17 (stock Z rated) on front, 255/40/17 (DiscountTire H rated) on rear. Because 255/40/17 does not overhang the rim of the wheel, and because it is actually 1.7% smaller in diameter, I predict the following combination for those who have the stock gs4(30) 17x8s. When its time for new tires, try:

255/40/17 Front
265/40/17 Rear

This would result in less than 1% change in mileage and odometer, since 265/40/17 is almost the exact diameter of stock 235/45/17.

I may just go with the combo your talking about. My 95 540i was 235/45x17 front and 255/40x17 rear. I did some checking and found out, as you have, that 265/40x17 would have been a better match, but the tires I wanted didn't come in that size.

Please post some pics. Can't wait to see how that setup looks.