Question about Stock Rim width - What is widest tire I can install on it?

[bambookid]

Hey everyone

I have a set of 91 OEM rims (15' and 16') and i see some people put wider r-compounds on them. I have on Khumo v710. I have 235 in the front and 265 in the rear. I don't plan to use spacers so i know the front will rub at full lock (and it does a little). My car is lowered on KW V3 about 1.25 inches and there's no rubbing on the fenders.

I just measured the Stock Rear Rim and its 8inches wide when measured from inside of the rim to inside of rim. It's 9 inches wide when measured from outside of rim to other side of rim.

I want to run this combination (235 & 265) for autocross and track application. Has anyone run this combination? if so, is it safe or is it not safe??? Will the rubber come off the rim from the lateral G when cornering in track and autocross?

If its not safe, what is the widest I can go without having any major problems?


Thanks,
Ed C.

 

[shrddr]

for autocross, you will be perfectly fine with those tire sizes. i have an NA2 so my wheels are a bit wider than yours, and i run 245s on the front (7" wide wheel), and 295s on the rear (8.5" wide wheel).

 

[nsxtasy]

I just measured the Stock Rear Rim and its 8inches wide when measured from inside of the rim to inside of rim. It's 9 inches wide when measured from outside of rim to other side of rim.

Rim widths are measured at the bead, as shown in this diagram:

The stock '91-93 rims are 15x6.5 and 16x8.

I like to keep my wheels and tires such that the wheel width is within the range approved by the tire manufacturer. All the more so for R compound tires on the track.

 

[Tamar]

The stock '91-93 rims are 15x6.5 and 16x8.

I like to keep my wheels and tires such that the wheel width is within the range approved by the tire manufacturer. All the more so for R compound tires on the track.

+1

I run Kumho 235 and 285 V700s on 8" and 10" wide rims and 205 and 225 Hankook Ventus RSS on the standard '91 rims.

The Kumho website doesn't quote a rim width for 235s (I guess they don't make them anymore) but they recommend rim widths of 8"-9.5" for a 245 and
8"-10" for a 265.

The problem with running wide tires on a narrow rim is that the tread bulges in the middle and reduces the contact patch, so while the wide tires may work for you, you will probably get better results from tires that are the correct width for the rim

 

[nsxtasy]

+The Kumho website doesn't quote a rim width for 235s (I guess they don't make them anymore) but they recommend rim widths of 8"-9.5" for a 245 and 8"-10" for a 265.

Note that you have to look up the recommended rim width for the specific model and size tire, not just the width. There are a lot of cases in which tires of the same width have different wheel width recommendations; for example, 205/45-16 tires are usually recommended for a maximum wheel width of 7.5" but 205/40-16 usually permit an 8" width.

The problem with running wide tires on a narrow rim is that the tread bulges in the middle and reduces the contact patch, so while the wide tires may work for you, you will probably get better results from tires that are the correct width for the rim

The other problem is that there is more flexing of the sidewall which builds up additional temperature and stress, which can lead to tire failure.