My wheel and tire setup - need expert advise.
 

Car: 370z
My ideal setup:
19x9.5 +40 in the Front (275x35x19 tires)
19x10.5 +22 in the Back (305x30x19 tires)

According to my calculations this should roughly give me 1-2mm more clearance on the inside and roughly 13-14mm extension towards the fender. The height on all for corners will be a tiny bit less than stock. I feel this will give a solid and proportioned upgrade from stock and with the right suspension setup will give it a great flush/slightly tucked look.

However, I have a couple of concerns...I see alot of 9.5 fronts ending up with a +22 offset, isn’t that over kill? How will that improve/change the handling characteristics of the car? Wouldn’t that square off all four corners rather than the back wheels having a wider stance (think Porsche)?

My goal is to have an aggressive street setup that I can basically take to the track with little to no modifications. It’s not entirely about the looks; I want to genuinely improve the handling with these mods.

You've got it right!

Unfortunately when it comes to cars you usually have to sacrafice performance in one area to gain in another. The lower the offset, the farther the wheel and tire sit from the hub. This will affect caster and camber gain on the front wheels when turning which can lead to a number of handling problems. Now, that being said, most people aren't going to be able to notice the difference between a +22 offset wheel and a +40 offset wheel, but it does make changes to your car's handling characteristics.

So you have to decide weather you want to sacrafice a little bit of handling for a better look, or the other way around. Its not going to be a huge sacrafice either way in this particular case though, but your theory is on point.

Thanks for the reply.

One of the reasons I ask however is because I heard 350's had understeer issues and that a setup similar to this would help out tremendously. That in turn, is then improving the cars handling. So I was just curious weather going to +22 in the front would ultimately reduce understeer and improve the cars laptime compared to a stock setup.

It's probably to soon to see the cars true potential. I'll keep an eye out on Mines and other real track proven tuners to see what setups they run on a street/track car.

There are many more things that will have a much greater impact on understeer than changing the wheel offset a little.

Could you guys explain to me when your offsetting? Why would you do that? Would a pair of 305 fit without using spacers? My last question is why is the tire side walls are always lower than the front (35 front and 30 in the back)? Is it for looks only?

305's with a good drag radial in the back would be my idea setup too. Either M/T DRs or the Nitto 555Rs. :D

We aren't talking about using spacers, just getting wheels with different offsets. The purpose can be to widen the track width of the tires or for that deep dish wheel look, either way you want to look at it.

Also, the sidewall question, in tire sizing the middle (sidewall) size is a percentage of the width. For example, on a 305/30/18, the sidewall is 30% of the width. On a 305/35/18, it is 35% of the width.

this should help you understand offset

Wheel Offset Calculator

why is the front offset so high?

So, what would you recommend as an ideal track setup (road coarse) for the 370z ? I dont really want to sacrifice handling but I figured a track setup would already give an aggressive look to the car.

In this case I just thought - bigger contact patch, a slightly wider track, a good coilover suspension - would give better overall handling to the vehicle AND retain a great look.

^^That is true. Contact patch will be the most important for performance as well as a good set of coilovers. A wider track is ideal, but accomplishing that with spacers isn't ideal. Small spacers wont make much of a noticeable difference either way.

Its a little early to tell the ideal setup for the 370Z since I haven't been out to a track with it yet, nor have I experimented with tire/wheel combos. Just stick with something that allows you to get a big enough tire to suit your needs.

So my setup should rock then!! I never mentioned spacers nor would I use them to widen the track. I just wanted to make sure the setup I originally mentioned would be a suitable street/track setup.

EDIT: I would like to add tho that the +40 offset I originally mentioned has been discontinued on the particular wheel I was looking into. I can only get it in +22 now in the front.

19x9.5 +22F
19x10.5 +22B

Those are the new specs. No spacers. That should outperform the stock setup with with all the mods I spoke about earlier, correct?

I don't think it will make much of a noticeable difference.

tire size
 

I have a question:
the new 370z rear tire size comes in 275/35WR/19's.
Later on I would like to change them to Nitto INVO tires, but the closest
size they have is 285/35/19, or 285/30/19. Any problems you see with
either one?

thanks.

None.