Front tire question - The Unofficial BMW M5 Messageboard (m5board.com)

Jessem · 12th June 2002, 19:57

I've performed a search on this, but no other posts seem to answer this question:

Has anyone tried using 255/35-18 front tires on the std BMS M5 front wheels? If so, has it helped understeer?

According to my calculations the OD should be nearly the same as the 245/40-18s. I'm not prone to want to replace 2 rims, etc etc to reduce the understeer and since I'm approaching front tire replacement time(and rears as well,) I was looking into my options.

Experience or advice will be appreciated.

RRoberts · 12th June 2002, 20:31

Jessem,

Take a look at the recommended rim width for each tire size. If I recall correctly, the recommended width for the stock 245-40 tire is 8.5 inches. Thus the factory tire selection for the M5 is already a little oversized for the wheel, and IMHO contributes to the understeer issue on the M5.

Regards, Dick Roberts

Bart Carter · 12th June 2002, 20:42

Dick is correct. A wider tire on the same rim would not perform as well. It would tend to roll under more when cornering and it would be harder to keep the tread flat when varying the tire pressures.

If you want to keep the same rims, you would be better off adding some negative camber to the front to decrease understeer.

Jessem · 13th June 2002, 04:33

I was looking at the Rim Width Range column as opposed to the measured rim width on Michelins tire sizing table. I always wondered how they could make a very low profile tire that would fit a range of rim widths and work as designed. Since I'm not looking to reduce tire wear, I think I'll stay with what I've got and not add any - camber either. Oh well, just looking for a cheaper solution.