I'm sure most don't want to hear about it unless you have times to show difference. BUT can you explain the feel factor between the sets of wheels?

 

absolutely, i understand i dont have times to post, but the 285s on the 8.5" wheels would roll so bad. i should say this was with equal sway bar and coilover settings, of which are more than likely far from optimal

 

Scotts posts/thread is mostly referencing the use of R-comps (hoosiers in particular). It isn't uncommon for stock classes to squeeze a 275 on a 6.5" wheel or 295, etc on an 8" wheel. Its been proven over and over to be quicker. That said, I would prefer a matched tire or ever so slightly stretched (10.5-11" wide wheel with a 285/295 on it). I just prefer the feel of that over my 285 on a 9" that I currently use.

 

yea, i realize my experience doesnt carry much weight due to street tires, off track, and tons of other variables, but i was just stating an experience i had related to the thread topic

 

I think it is a preference of contact patch vs roll and characteristics of the sidewall when the tire is like this:

/_\ straights
/_| in turns

On the track, I noticed a HUGE improvement in handling when I went with a smaller rim and a wider tire on a square stance.

When I was stretched, I had too much rollover. With tighter suspension and very little sway, I was actually lifting in the turns - losing my contact patch. The above worked for me - on the track. I don't dodge cones that much anymore.

 

wait, so some are handling better with fat tires on a skinny wheel? how does that work? what sizes are you talking here?

 

Given those 3 changes (smaller rim, wider tire, square set-up) I'm curious if most of your handling benefit came from the square set-up, which I assume it would.

Depends on how one defines fat and skinny. For example, a lot of guys run 9" wheels with 275 tires. That's probably the most common set-up (for both 17 and 18" wheels).

 

Except for multi-time national champion Jason Isley's BS RX8. He was quicker running 245s on his car then the 285s that everyone said was the winning tire size. Again, test, test, test on your own vehicle. Also, wheel and tire weight (and MOI) are more important on a lower horsepower car.

 

Can anyone (Scott, Beta, etc) measure the tread width of a 285 A6 mounted on 10.5" vs 315 mounted on a 10.5" wheel? Not overly concerned about fitment issues with the +15.....I will make them fit . Thanks in advance...

 

I posted a picture of them at some point - probably in the NorCal Autox thread. The difference was significant, probably over 1/2". I was wondering if they would crap onto the +15s as well. I put 315 R888s on a 10.5 +43 and it fit easily, but I don't think it would fit with a 25mm spacer by any means. At one point I had 305s on 10.5 +18s, and they rubbed like a mother (no fender mods).