Staggard Fitment: effect on performance

[jbradsh1]

I mentioned in an earlier post that I'm considering getting 18x8 front and 18x9.5 rear TSW wheels along with 245x45x18 and 275x40x18 tires. Anyone know how this will affect handling? Off the line traction at the track? Ride quality? Noise, with Michelin Pilot Sport A/S tires? Thanks in advance.

Also, any problem with proper fit, assuming front wheel offset of 40mm and the rear's at 45mm?

[PantherGTBlack]

I know when I did some testing for TireRack at South Bend I had a 295 on the rear and I noticed that it made the car have a slower turn-in rate, if that makes sense to you. I would say a 275 rear would be just about perfect, you will get good straight line traction and it shouldn't affect the turning rate too much.

[GRRRR8]

You should be using a 275/35 on the rear. Sprung weight does effect performance, so the heavier the wheel is it can cost a little ET, but it is offset by the added width for better traction.

[jbradsh1]

Everything you guys said makes sense to me. Just so you'll know, the 275x40x18 has the same diameter as the 245x45x18 tire, so the ride height will be the same. The unsprung weight increase with bigger tires and wheels I'm a bit concerned about, although the Michelin tires I'm looking at weigh 27 lbs. & 30 lbs. (front to rear), so that's OK, I just don't know the weight of the TSW wheels yet ... compared to stock. I'll find that out tomorrow. Never driven a car with staggard fitment is why I was asking. Thanks.

[GeorgeInNePa]

I know when I did some testing for TireRack at South Bend I had a 295 on the rear and I noticed that it made the car have a slower turn-in rate, if that makes sense to you. I would say a 275 rear would be just about perfect, you will get good straight line traction and it shouldn't affect the turning rate too much.


What wheel and offset did you use to fit a 295? What tire?

19x10, 55 offset?

Thanks?

;)

[PantherGTBlack]

What wheel and offset did you use to fit a 295? What tire?

19x10, 55 offset?

Thanks?

;)


19x9.5 with a +35mm offset...it didn't stay on the car as you can tell by my signature. We tried that just to test how big you can go. It looked mean as hell that way but they rubbed like a mutha. I'm currently running a 255 on a 9.5" wide rear with a +45mm offset and no rubbing. I know for a fact I can go larger than that. I had rubbing with a +35mm offset on a 9.5" wheel with a 255.

The 295 tire was a BF Goodrich KDW 2, I think that is the right name. Regardless it is the one with the crazy tread pattern. I'm going to go back to these for my next set of tires. Probably run a 275 so it doesn't affect the handling too much but will still get good straight line traction for the cam, etc. that I want to put on in the near future.

[p71]

It is just KDW, tire rack adds the 2 to distinguish the new from old tread patterns. Badass tires regardless.

OP: wider rears contribute to increased understeer.
Your best bet is to go with wider rears that weigh less than stock so the problem Charlie mentioned is negated. also add a nice heavy set of subs to the rear to shift weight balance that way to counteract the understeer and you are good. Or if sound systems are not your thing, get some adjustable sway bars.

[EcoBrick Bob]

You can change the steering feel with tire pressures. My 285's feel great at the higher recommended pressures in our manual. Since I'm an old foggie, propably best with more understeer!

[jbradsh1]

You can change the steering feel with tire pressures. My 285's feel great at the higher recommended pressures in our manual. Since I'm an old foggie, propably best with more understeer!

Good point, but you know, power induced oversteer will get your heart rate up, in case you haven't been getting your exercise in!

[Ktlplxm]

Another thing to consider, is that the 295 optimally shouldn't be on anything smaller than a 10", a 10.5" is preferred. When the sidewall is pulled in that much, handling is almost always compromised in some form or another. A perfect example is when we were doing skid pad test on the Nitto NT01's. When we initially had the 315 on a 10 inch wheel the handling left a little to be desired, once the same tire was swapped on to a set of 10.5, lateral G's picked up noticeably

[PantherGTBlack]

Another thing to consider, is that the 295 optimally shouldn't be on anything smaller than a 10", a 10.5" is preferred. When the sidewall is pulled in that much, handling is almost always compromised in some form or another. A perfect example is when we were doing skid pad test on the Nitto NT01's. When we initially had the 315 on a 10 inch wheel the handling left a little to be desired, once the same tire was swapped on to a set of 10.5, lateral G's picked up noticeably

Makes perfect sense. If the wheel is too narrow for the tire, it will allow too much side-wall flex which would affect the lateral Gs, right?

[locrzn#92]

The tread should not be narrower the the wheel, especially with the low pro tires of today. I see this all the time when cars come for wear issues or other problems like curbs. You can just tell someone led this person in the wrong direction. I had a 745 bimmer come in recently that had 22's on it. The tires up front were about 1'' to narrow and I realized after we pulled the wheels off, they didn't have to correct offsets and backspace on the wheels and the tire was to close to the strut to run the correct size. So, someone had put a 25 series tire on the wheels so they wouldn't hit the strut, talk about a rubber band, it looked horrible and sidewall were all bulged out and the tires were wearing like shit. So, he's got a problem and were gonna have to put the same size tire on again because he loves the wheels and doesn't really care how it rides or how it looks. Hey, sold 1000 bucks worth of tires and you just can't fix the obvious sometimes. The customer is always right.