Square tire setup on staggered rims? (255/35/19 tires on 8.5x19 front and 9.5x19 rear)

[ElChanclo]

I just got an incredible deal on a set of 99% new Michelin pilot AS4 255/35/19 tires (DOT 4022). I happen to have a set 8.5x19 and 9.5x19 rims I bought for track days, but I can also use the OEM rims for the track, since 255 is too wide for the 8.0" OEM front rims.

Is there any reason you wouldn't put 255/35/19 tires on 8.5x19 fronts and 9.5x19 rears? Is 255 too wide for the front of a stinger? Tires are specd for "Rim Width Range" of 8.5"-10.0" on the Michelin website BTW.

 

[Snicklefritz]

what is the offset?

 

[ElChanclo]

what is the offset?

19x8.5+33 and 19X9.5+35

Whose idea was it to measure rim width in inches and tire width in mm, and the aspect is in % ?

 

[Snicklefritz]

lol, interested, intelligent minds want to know. but no answers I suspect.

19x8.5+33 and 19X9.5+35

Whose idea was it to measure rim width in inches and tire width in mm, and the aspect is in % ?

those offsets should work with 255 at all four corners. but the individual rims should be double checked to make sure. the rear for sure isn't any trouble. the front, if you did have questionable clearance, could reduce offset further with a spacer, probably. again, the lugs are only so long. I wouldn't want to do this on my own. get a pro to vet your setup before you commit.

 

[ElChanclo]

lol, interested, intelligent minds want to know. but no answers I suspect.


those offsets should work with 255 at all four corners. but the individual rims should be double checked to make sure. the rear for sure isn't any trouble. the front, if you did have questionable clearance, could reduce offset further with a spacer, probably. again, the lugs are only so long. I wouldn't want to do this on my own. get a pro to vet your setup before you commit.

Thanks for the heads up, the clearance is good but I'm concerned about steering on 255 up front. Also double checking if I've overlooked anything before forging ahead.

 

[Volfy]

Well, if you already bought the tires, then go ahead, mount them up, and go tear up the track. You'll have a ball of fun. Fitment-wise, your front wheel width and offset are spot on. Rears probably okay too.

That said, four 255s on staggered wheels are a bit odd. Because the fronts are your steering wheels/tires, ideally, you'd want them to be better supported on wider rim width for better stability under lateral acceleration (cornering forces). This reduces tire squirm, sharpens steering feel, and quickens corner tip in. This is why stock setup is 225 stretched over relatively wide 8" rims.

The rear wheels OTOH has different requirements. Because they are the driven wheels - or primary driven wheels in an AWD - tire compliance ranks a bit higher priority over tire support. Given a choice, one would trade a bit of lateral stability for a bit more "give", which helps keep the tire adhere to the track surface. This is particularly important on launch and when powering out of corners, especially if the track surfaces are a bit rough. This is why stock setup is 255 over relatively narrow 8.5" rims.

Your setup is biased exactly the opposite. Fronts are mounted on 8.5", which is the minimum recommended rim width, while your rears are mounted on 9.5, near the maximum width.

Another effect of your front and rear rim width differences is how they affect the effective tire damping. All tires act as a spring that combine with your coil springs to suspend your vehicle. A better supported tire will act as a bit stiffer spring, compared to the same tire that is less well supported. This means your effective spring rate in the rear will be ever so slightly stiffer than the front. This will affect your car's cornering attitude the same way a slightly stiffer rear coil spring (or rear anti-roll bar on stiffer setting). The resultant effect is less understeer or more oversteer. This is not necessarily a bad thing, given the fact that stock Stingers tend to understeer on corner entry. Still, you need to be aware of this and take it into consideration when setting up your suspension tuning.

If you're just out there to have fun, these differences won't be super pronounced. Unless you're seasoned track rider and know your track roller very well, these effects will likely be subtle enough not to bother you.

 

[Snicklefritz]

Well, if you already bought the tires, then go ahead, mount them up, and go tear up the track. You'll have a ball of fun. Fitment-wise, your front wheel width and offset are spot on. Rears probably okay too.

That said, four 255s on staggered wheels are a bit odd. Because the fronts are your steering wheels/tires, ideally, you'd want them to be better supported on wider rim width for better stability under lateral acceleration (cornering forces). This reduces tire squirm, sharpens steering feel, and quickens corner tip in. This is why stock setup is 225 stretched over relatively wide 8" rims.

The rear wheels OTOH has different requirements. Because they are the driven wheels - or primary driven wheels in an AWD - tire compliance ranks a bit higher priority over tire support. Given a choice, one would trade a bit of lateral stability for a bit more "give", which helps keep the tire adhere to the track surface. This is particularly important on launch and when powering out of corners, especially if the track surfaces are a bit rough. This is why stock setup is 255 over relatively narrow 8.5" rims.

Your setup is biased exactly the opposite. Fronts are mounted on 8.5", which is the minimum recommended rim width, while your rears are mounted on 9.5, near the maximum width.

Another effect of your front and rear rim width differences is how they affect the effective tire damping. All tires act as a spring that combine with your coil springs to suspend your vehicle. A better supported tire will act as a bit stiffer spring, compared to the same tire that is less well supported. This means your effective spring rate in the rear will be ever so slightly stiffer than the front. This will affect your car's cornering attitude the same way a slightly stiffer rear coil spring (or rear anti-roll bar on stiffer setting). The resultant effect is less understeer or more oversteer. This is not necessarily a bad thing, given the fact that stock Stingers tend to understeer on corner entry. Still, you need to be aware of this and take it into consideration when setting up your suspension tuning.

If you're just out there to have fun, these differences won't be super pronounced. Unless you're seasoned track rider and know your track roller very well, these effects will likely be subtle enough not to bother you.

I always enjoy your posts. this one particularly informed me. I've wondered about staggered rims on squared tires and this explanation of the dynamics has been very informative. I don't tack, but I imagine doing it, and tuck information like this away for possible use later. and, it's just fun to know things. thanks for sharing.

 

[djerickd]

run it

 

[ElChanclo]

Well, if you already bought the tires, then go ahead, mount them up, and go tear up the track.

Sorry I phrased that weird. The AS4 will be for daily street driving on the new rims that were intended for the track. Instead I'll put the PS4* track tires onto the OEM rims as they're same as OEM tire sizes. Unfortunately the 255 AS4 are too wide for the 8.0" front OEM rims.

Your setup is biased exactly the opposite. Fronts are mounted on 8.5", which is the minimum recommended rim width, while your rears are mounted on 9.5, near the maximum width.

That's really my gripe, steering with 255 on a narrower rim. That and the short sidewall for daily driving. Worst case scenario I sell them and put the difference towards 18" all seasons.

 

[Volfy]

Okay, a lot of what I mentioned apply mostly to the track, where you can safely push the car's limits - and yours, as a driver. if it's for road riding, those subtleties might still present themselves, but you might not notice them, even with fairly spirited driving. Most sane drivers do not carve canyons at anywhere near their limits. Even on 2-wheels, I limit myself to 6/10th track pace max, when slicing and dicing twisties. Still plenty fast enough to be of much fun, but with ample safety margin and reserves to handle the ever present sudden surprises and unforeseen contingencies on public roads.

Also, for road riding, you would want even more tire compliance. Unlike at the track, where I don't give two sheets about ride quality, for daily driving I absolutely do care about a nice ride. So, the calculus is yet again different. There is nothing wrong with 255 mounted on 8.5" rims. We run square 255/40R18 on 18x8.5 Enkei on my son's G70. Handling is still plenty sharp, but ride is much improved. It's all relative, and everything is a compromise. The same attribute that can be construed as a negative in one application might - and often do - manifest in a positive manner in a different application.

I mentioned the finer points, so those who care to understand and appreciate them can hopefully use the knowledge to make more informed decision when picking tire and wheel sizing - and evaluating them - for various applications.