Learn me: tire-staggering for FWD

Say someone wants to dial out understeer and have their car rotate more so - I run a square setup on my Mustang, but with a FWD car (say, an 8th gen Si), I don't see why not.

What's the proper way to do it? Same size rims all around with just wider tires up front, or do I go a 1/2-inch or full-inch wider rim up front with wider tires? While we're on the matter, let's say we want to get rid of wheel width gap in the rear wheel wells. I'd run a spacer in the back to keep a square setup, but that does mess with handling?

I have some experience with this at autocross.

At first I battled with understeer in my turbo escort running a 15x7, 205 hoosier square setup.  It wasn’t great.

Then, actually against the recommendations of several people, I threw some 225 hoosiers on up front (same wheels). Suddenly, the car was far better, at least to me.  The wide tires on the narrow wheels made things a bit less crisp, but both the rotation and max lateral grip was much improved.  Lift-off oversteer was easy to create, but controllable.

Next stage for me is a new set of wheels, 15x9 up front and 15x7.5 in the rear… along with an adjustable rear sway bar in place of the non-adjustable upgraded one I have now, for some tunability.  And since I can’t just change one (or two) things at once, I’m also switching to the BFG Rival S … 245/225 sizes. 

Regarding wheel spacers in the rear, another way to improve rotation etc. on a fwd is to make your front track wider than the rear track.  By adding spacers in the rear you’ll actually be tuning some of that out.  This could actually be a useful tool, depending what kind of results you get with the reverse-staggered tires (i.e. too loose? Try adding the spacers.)

In reply to Dootz :

Audi does this from the factory on the RS3 and I think the TT RS, but I'd have to check on the second one.

I've also see folks run the same size tire but run them on skinnier rear wheels.  This allows tire rotation for life/budget.  Apparently the less square rears create the desired rotation.

I've seen everything from different wheels to full on tire stagger.

The popular move for the 8th gen civic is to do a 255 on a 17x9 up front and a 225 out back, I believe on a 17x8.

On my '95 Neon ACR, factory 15x6 wheels all around:  I ran 195s up front and 185s in the rear, in a corrsepondingly taller aspect ratio.  It rotated nicely under almost all driving conditions, when coupled with the stock ACR rear sway.  If a beefier aftermarket rear sway is available, it might do the same trick for you without requiring different section widths.

But all the cool kids put wider wheels in the rear for extra dish effect, don't they?

I knew a guy who ran a fairly well DSP prepped '02 GTI 1.8T. It had 18x10 285 A6's up front and 18x9 245's out back.  It was definitely quick and would rotate on demand. He had a hell of time staying ahead of it, driving wise. He ran spacers to get the wheels to clear the suspension.

The V8 version of the Pontiac Grand Prix actually used wider front wheels and tires from the factory. Unusual but cool.

https://www.caranddriver.com/reviews/a18202165/pontiac-grand-prix-gxp-road-test/

I was about to ask about putting my 285s on the front and 255s on the rear of my mustang for track days.  330hp to the wheels on an 08 mustang, why not, I have adjustable bars front and rear to dial it in if needed.

I can tell you that 255 RT615's on the front and old, hard 215 all seasons on the rear on a damp asphalt surface makes an excellent drift machine.

akylekoz said:

I was about to ask about putting my 285s on the front and 255s on the rear of my mustang for track days.  330hp to the wheels on an 08 mustang, why not, I have adjustable bars front and rear to dial it in if needed.

I wouldn't.  With RWD, start square unless you can't fit enough tire up front or can't get acceptable steering geometry / feel / behavior with the wider tires up front.  Then stagger (wider in rear).  Reverse stagger on RWD would be an absolute last resort after exhausting every other chassis / suspension option to get decent balance out of the car.  

I used to crush souls in my 8th Gen Civic Si at the local autox venue. 225/45/17 Hankook RS-X at all four corners and a big rear sway bar. I had a front strut bar as well but the effects of that are debatable. 

I never found the understeer in those cars all that bad compared to Focus ST or a Kia Forte Koup. 

rslifkin said:

akylekoz said:

I was about to ask about putting my 285s on the front and 255s on the rear of my mustang for track days.  330hp to the wheels on an 08 mustang, why not, I have adjustable bars front and rear to dial it in if needed.

I wouldn't.  With RWD, start square unless you can't fit enough tire up front or can't get acceptable steering geometry / feel / behavior with the wider tires up front.  Then stagger (wider in rear).  Reverse stagger on RWD would be an absolute last resort after exhausting every other chassis / suspension option to get decent balance out of the car.  

I could have sworn he was being sarcastic, no? Hard to tell with just words.

Caster,camber and a big rear bar removed any noticeable under steer on my ZX2SR.

It's suspension was slightly rear biased, so that helped.

Ran the tires square, easier rotation.

I run 245s front with a 205 on back of my neon.  It works well for me.  Its had some time to dial it in though with different spring rates and sways and such.

I did it on a Honda Insight and a Dodge Caravan, and it did exactly what i wanted it to. 

The rear tires on my Insight are 165/50/15! 

I'd have to look, but iirc, I had 245front and 225rears of Conti ECS in 18", and with probably a 10-20mm differential in front to rear track width, on the TL that was originally intended for the Sonata a couple years ago.  Stock suspension-ish, and still needed an 8psi cold differential before it got oversteery.  It's hard to tell if it was much faster compared to the 235square setup it ran in 2017.

However, I kind of wish that "Bulldog Stance" was more of a thing than it has been so far.  ymmv.