go smaller w/tires?

[nostatic]

16x7/8s, was running RA-1s in 225/50/16 and 245/45/16. I was getting a lot of wear on the outside edges of both front and read, but especially front (at the track). I need to get a new set, and was thinking about going 205/55/16 and 225/50/16. The reasoning being that the tire would be a bit more "stretched" width-wise on the rim. I don't know that I can get any more negative camber withoug modifying the spindles up front, and I'm stuck with stock t-bars at least for another 4 events (and likely longer if my budget stays hammered). I know I'm giving up a bit of width going to the smaller tire, but maybe my contact patch will be better since the tire is a better "fit" for the rim?

anyone done the experiment?

[porschenut]

How were your pressures? Maybe you were running them a bit low....I have the same size rims and run the same size tires, but I don't have that problem. My camber is -0.75 front, -1.5 rear.

[nostatic]

hmm...maybe I was about 32 front, 34 rear hot (right after coming off a session). Cold they would be well under 30.

[nostatic]

Really? I know that Hoosiers like higher pressures, but I thought that the RA-1s like it a bit lower hot. Well, I'll try that with the next set...

[87coupe]

I would consider 225/245 on 7/8 to be "pinched" and 205/225 to be normal, "streched" would be 205's on the 8's. I would think a "pinched" tire would have more sidewall flex in turns and thus wear the outer edge quicker.

[dd74]

Off the bat, you'll have stiffer sidewalls running tires with less width. That might alleviate t-bar needs for a little while - but I'm not positive about that.

I considered this option as well to battle sidewall flex. 195-50-15s on 7" and 205-50-15s on 8", but with 15-inch wheels, at least the 205-series isn't recommended for 8-inch widths.

So I instead put more air in my tires - much more - and it worked out pretty well.

[dd74]

BTW: Todd, you going on the Mul run tomorrow?

[drums]

I found 16" X 7+8" to make the rear twitchy too. I put spacers on the rear to bring each side out 1 1/8" and it cured the problem.
Drums

[edward993]

I've got 7s/8s but because my SC is pretty low and I get awefully close to rubbing the left front on already rolled lips, I run 205/245 and the rear feels planted (street rubber on the track). Sure, I get some understeer in slower corners, but driver input can address much of that. In faster bends the car feels very neutral and can be rotated easily. For reference, I've got a modest suspension with only 22/28 t-bars and 22/21mm carrera sways, OE rubber bushes (old) all around.

Edward

[Bill Verburg]

The rule of thumb is that a tire mounted on the widest wheel will perform better than, the same tire on a narrower wheel. There is definitely a point where the narrower tire on a wider for its size wheel, will outperform the next size larger tire on a smaller wheel.

I came to this conclusion wrt to my own car a while ago, a 265/40 on 9.5 will perform at least as well as, and probably better than, a 275/40 on the same rim

[87coupe]

Big tires on small rims are good for going in a straight line, not going around turns.