Tire Width Differences in Performance

[RobNoLimit]

This is fantastic info. Rob, using the 17x9 example is the 255/40/17 the most appropriate width tire you would recommend on that rim? Thanks.

That's the best choice I have come up with. A 255 tire is apx 10.1" wide, Bridgestone specs that tire at 10.2", with a rim spec of 8.5" to 10" wide. A 9" rim is really 9.8" or so wide, (outside lip to outside lip, depending on rim manufacturer). So it's a pretty nice fit. I have been trying to run a wheel that is close to 1/2" or 3/4" (O.D.) narrower than the O.D. tire width. This matching seams to support the sidewall/contact patch the best. For 315 tires we have been using a 10 1/2" wheel lately with good results.
On my current project, I started out focused on a 275 tire, and although that is common in an 18" tire, it's not in a 17". After a lot of tire research I chose the 255/40/17, it has a good choice of tires/manufacturers from 400 TW all season tires to 40TW R-1 compound slicks. The difference layed out like this. The 255/17 combo weighs 40 lbs, tread block is 10.12" wide mounted. The best fit I could find for the 275/18 weighed 47 lbs, with a tread block 10.78" wide. The total difference in the contact patch is 1.8 sq.in. - but, if you follow the rule of only using 70% of the contact patch at any one moment, the usable difference is 1.26 sq,in. At some point there comes a point of diminishing return for a bigger, heavier tire. - This of coarse is assuming that you are maximizing the the tires full potential. So the question becomes, would you add 28 lbs of rotating un-sprung mass to gain 5.04 sq.in. if contact patch?
- BTW, I pruchased a set of Wed's Racing TC-105N wheels and 255/40/17 tires, mounted/balanced and shipped to my door, for a touch under 2800 bucks. - That's how I roll