On tire rack under specs on the tire itself. They have a "section width" and "tread width", what is the difference?
Thanks

Jay

 

Here's my speculative answer -

The section width is the number stamped on the tire - measured in MM from sidewall to sidewall while the tire is mounted on a "specified sized rim". No one seems to know the size of the specified rim.

Tread width is, well, the width of the treaded part of the tire. This can be different than the section width because some tires have more rounded sidewalls than others.

 

It's listed in the charts for each line

 

Which one applies when comparing replacement tires to the s02, I am looking at the re750 245 rear and 225 front. the tread width is close in spec, but the sect width is much bigger.

thanks

 

unfortunately its not that easy...as per many discussions.

Yes, the tread width of the OEM S02 is close to a 245 treadwidth, however, a 245 is reaching the upper limit of the stock rim width. THe discussions suggest that if you put a 245 on a too narrow wheel, the tire will stretch and crown, causing LESS contact patch than the 225.

Try page 2 or 3 of this wheel and tire forum, and there's a good thread about it.

 

section width is the MEASURED distance across the entire surface of the contact patch, from sidewall to sidewall.

tread width is self-explanatory.

 

I would argue that sidewall to sidewall measurement can vary GREATLY from contact patch measurement.

It depends on the inflation of the tire, alignment of the car (camber), sidewall stiffness....