Will running 235/255 give too much oversteer?

I wanted to run RPF1's in 17x9 +45 all around, but wanted to stagger the tires. I would love to have a 225 in the front. but the wheel is too wide.

Plus i'm not confident in running 245's all around.

 

255 all the way around!

 

If you wanted to stagger the tires, why'd you get 9" width all around?

I'd say 235/40-17 fronts (I wouldn't go with 235/45) and 255/40-17 rears shouldn't be a problem, handlingwise. IMO the effects of treadwidth stagger on handling balance on a street car on the street, are often greatly exaggerated...

I think your real worry is tire rub.

 

The problem is the 235/40R17 is going to be short on the front and can throw off the anti lock brakes. I suppose you could run the 235/45R17 with the 255/40R17 but they are 4/10" taller than the stock front tires.

 

Planning ahead I guess, incase i wanted to try a non-stag. setup in the future and it was a good deal.

How about the balance on the track/auto-x? I'm not too too concerned about the street as i don't try to do anything stupid.

As for the tire rub, would it rub that much with 235/40? I see the common setup is 245/40 for non-stag. and with rolled front fenders it seems to be fine.

Jim - Is there a way to compensate for the shorter tire with ABS, how will a 245/45 effect ABS? in case i decide to stick with non-stag.

 

235/40-17 is .5" shorter than 255/40-17. 235/45-17 is .4" taller.

IMO, better for the fronts to be a bit shorter than the rears rather than a bit bigger.

1. Taller fronts than rears moves brake bias rearward (not the conservative direction)
2. Shorter fronts will be less likely to rub, which may be an issue with 235 width on +45 offset
3. Aesthetically, fronts that are bigger in diameter than rears doesn't look all that hot (subjective)

FWIW, I ran a pretty extreme difference in diameter front/rear: 205/45-16 (23.2") with 225/50-16 (24.9") for a few track events (not by choice, track tires that were given to me). The ABS worked fine, but I could tell at the track that braking was overly biased to the fronts. Not a huge deal, and safer than bias being moved rearward.

 

My last track event I ran 235/255 RA1's (i forget which size 235's) on my stock CR (stock sways, stock suspension). The CR has a tendency toward understeer stock, imo and I found the 235/255 worked well. Running 0 toe I found that I could trailbrake quite well and (as long as I didn't make a dumb mistake) was decently predictable.

I probably wouldn't try it on my old MY02 though. Seems like it would lean toward too much oversteer (if stock and within stock alignment range). In my MY02, I ran 225/245 (16") RA1's with a big front sway bar and liked that balance. I think if you're comfortable with a fairly loose car, a 235/255 with maybe a CR front bar would work well.

BTW - I didn't mind the odd tire height for 235's because they were only seeing track miles.

 

Many a curb/ditch has been found by S2000 drivers who didn't think they were trying to do anything stupid!

But anyway, I wouldn't worry at all about balance at the track. Either way, you have to adapt to the early AP1's tendency for initial oversteer followed by neutrality. If you sense the initial oversteer and get off the gas, you're likely to spin. Takes a little getting used to...
FWIW, I've driven at the track with very little treadwidth stagger (225/50-16 fronts, 245/45-16 rear VictoRacers, 0.5" treadwidth stagger) and the balance was totally workable. Oversteer is easily controllable with driver input, and for me, it's better to have modulatable oversteer than unresponsive understeer.

Lotsa folks run 255's up front with no problem. But 235/45's are quite a bit taller. I'd definitely go with 235/40's to minimize likelihood of rub.

The ABS will work fine with 24.5" fronts and 25" rears. It's only a 2% difference, and as I mentioned above, I've run with 7% shorter fronts and it's not a big problem. Overworks the fronts in braking, but that's more stable anyway.

 

Just run the typical 225/45 up front, it will be a safe stretch.

 

You'd want 245/40-17, not 245/45.