Determining the proper width size of the tire
 

How would you go about determining the perfect width of the tire in the front/rear relative to your application and power of the car.

I'd imagine for a car like this going any wider than 8inches in width would be too much unless you're hitting 330+hp.

I'm thinking a 7 inches in the front and maybe 8 inches in the back.
However, I have a feeling this car will come stock at 7 inches front and back.

Staggered is fine if the suspension is setup or it (ie setup for oversteer). If not having a traction bias in the rear is going to mean understeer. I'd wait until you were traction limited due to power then change rear tires and then change springrates/sway bars/alignment etc

That's not fully true. I used to know one Mx5 that was only 200whp-ish and using 9" on the rear and it was perfect size (don't oversteer or understeer). Like Dave state, it's all up on suspension setup.

I'm not gonna be staggered unless the car comes staggered.

+1
I'd rather keep it simple, hopefully Toyota agrees.

another +1. I like the look of staggered, but I think it's overkill unless I make some serious HP in this car, anything near stock I think should be kept the same, alot of engineering went into this car, and I trust that Tada-san and his cronies know more about correct engineering than I do :bonk:

Id agree that 7 all around in stock form should be ok, but it wont take much more power to reach the limits of that size. I would probably get rims to accomodate future plans.

With the 370z when you upgrade to the 19" wheels and tire grip increases from .92g to .98-.99g with the width only increasing by .5. I wouldn't go too aggressive with the width if I wanted to.

Subaru's PR already said 215/45/17 tires, so they will not be staggered. Since the tires aren't staggered then the wheels won't be either. OEM's tend to fit tires to the correct wheel size provided by the tire manufacturer.

For that size tire the appropriate wheel widths would be 7.0-8.0 for most performance tires. I honestly doubt they'd issue a 17x8 wheel so my guess would be 17x7 all around.

215/45-17? Ugh. Why an oddball size, I wonder? At least mfgs are starting to make some decent tires in this size now...though they can cost more than the larger, more common 225/45-17.

The other factor to consider when contemplating changing tires/wheels is the weight of the package. A car this light (2600ish lbs) and with this amount of power (190ish HP) will definitely feel different with just a 5lb per corner change.

Oddball size? That's common size. I use that size for my DD wheel.

Car is built around the tyres, not vice versa.

I would have preferred 225/45-17 as well but there are enough options for the 215/45-17 that I'll be able to find something.

At least there are RE11s, Star Specs, AD08s, RS3s and XSs in that size.. and some closeout R comps that are likely pointless to use at this point..