Da Groj

So I decided to go with the Hancook’s RS4 and my next question is should I go with a 275/40 profile tire upfront and 285/35 rear or can I just do 35 and 35 front and rear.
The difference I see is that the 40 profile tire has a Higher load index of 1700 plus is 1” taller, the 275/35 load index is 1500 for the fronts and also the 275/35 and 285/35 have almost identical overall tire diameter... better balance set up? Should i not worry about the load index?
My car is a 370z roughly 3200lb and new wheels are front 18x9.5 and rear 18x10.5.
Im trying to reduce understeer!
Im currently running front 245/40/19, rears 285/35/19 on stock wheels.
What do you guys think?

Thanks,

-Jorge

Might be nit picking here but how are you able to fit 245/40/19s and 285/35/19s on an 18" wheel

Also, what tires were you running before?

Been running on 245/40/19 and 285/35/19 indy 500 on stock 19 wheels.
I bought a 18x9.5 18x10.5 set of wheels just trying to fit appropriate size for autocross.

Reducing the difference in width between the front and the rear tires will help reduce understeer. But, just changing from "average" tires to "kick-ass" tires will also have a great effect.

I'd start with the tire change mostly. Don't go nuts with the tires sizes. If you're running 245/285 now, try something like 255/285... just a slight difference. You want to figure out what kind of difference just a better tire is going to make.

From there, there's also a little bit of "driver tuning" involved. You can learn to drive around a little bit of understeer. A high-powered rear wheel car typically SHOULD be set up to slightly understeer so that you can put power down earlier/harder coming out of a turn without kicking the tail out so easily.

Tires first. Try to keep the overall diameter of the tires within about 1/2" of stock if possible.

You also didn't mention the offset of your new wheels. That's something you need to be considering. Moving the offset in or out AND fitting a wider tire can cause clearance problems.

Thanks Loren, base on what you say and what Hankook offer for tires the 275/35, 285/35 are closer to stock diameters so I ordered those. Ready for more driver tuning!