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.

I am still a tad confused with the 370 offsets. Would it be possible to run 19x9F +25 tire 255/35 and 19x10R +25 tire 285/35 without any issues (this would be for the sports package)

If you go from a stock 275 to a 285, it will make the speedometer inaccurate wont it ?

^^^No, the overall diameter is what changes speedometer calculations, not width.

i think the front tire set up of 275 is to wide. Won't that hurt the performance of the car? If you look at the lambo and other exotics there tire set up for the front isn't that wide usually.

Lambos and other exotics are usually mid-engine cars with more weight over the back than the front so much less tire is needed. Skinnier tires up front is also the factory's way of dialing in understeer to vehicles for safety purposes.

I run a 295 up front on the time attack 350Z, and will be running a 275 up front on my track setup for the 370Z. Going with a wider front tire will hurt the vehicle's turn-in and straight line speed with the added weight and rolling resistance, but what it gains in corner entry and mid corner speed usually far outweighs the losses.

Ah I get it. Thanks for the info.
Just curious what size are you going to use for the rear tires? since it's a front engine, other than for better cornering, more weight and what not is there a bad thing going wider on the rear for the 370?
Going 270 up front will you need spacers?

No you will still need bigger tires in the rear, just usually not as big of a difference between front and rear as say a mid or rear engine car.

Because of the time attack class I am running the car in I am limited to a 285 max width tire. If I wasn't limited I would probably do a 305 in the back and probably no more than a 20mm difference between the front and rear.

DD,

What is the widest tire you would recommend for a 10" rim ?(rear) Could I get away with a 305/30/19 ?? (Stock sport rim with 5mm spacer)
I really would like to try a set of the Nitto Invo's, I wanted to go with a 295/30/19, but they don't make this size. seams pointless to only go to a 285.

Braden

According to the Nitto web site the rim range for the 305.30.19 is 10.5 - 11.5" with their measurements taken on an 11" wheel. If you used the stock 10 it would pull the sidewalls in a bit.

I mounted a Bridgestone RE-11 305/30 R19 to the stock 10" wheel. The sidewall gets pulled in a tiny bit but otherwise fits perfect.

Thanks Chris, I didn't think it would be a huge problem. When I put Nittos on my Mini Cooper S they recommended a 7.5 inch rim for a 225 tire and I'm running a 17x7 with no problems. I really want to try out those Invos because of the non directional tread, and the only choice would be 285/35, 285/30 or 305/30. The 305/30 seams to have the best sidewall height IMO.

did you take any pics when you mounted it??

I think the Invo's are directional as they have different compounds in different sections. The overall height is pretty close, 26.2". Mine are 26.3" rear and 25.6" front and no problems with the VDC, still fully functional.

I'm going to take some pics today of the mounted tire so you can see the curve and contact patch. I went to yesterday but my camera battery was dead.

Pics.

Rear contact patch. Notice how the sidewalls are pulled in slightly, so the contact patch isn't a full 305 that it would be on a larger rim. The upside is that the tires might last longer before they cord in a camber limited environment.
http://www.the370z.com/members/chris...larger-rim.jpg

Front contact patch. Much better here, nearly a full patch.
http://www.the370z.com/members/chris...5-35-9-rim.jpg

Rim bulge from behind.
http://www.the370z.com/members/chris...bulge-rear.jpg

View from top of rear fender.
http://www.the370z.com/members/chris...top-fender.jpg

View of fender rear well.
http://www.the370z.com/members/chris...-clearance.jpg

Probably should of put these somewhere else, didn't mean to highjack this thread.

Is that a pic of the 305?

Chris,

thanks for the pics :tup: gave you some rep points for that.
Do you have any full shots of the whole car?, I'll check your gallery.
yes, the Invos are non-directional, so you don't have to take them off the rim to rotate, just move them from side to side. :tup:

thanks again.

All the pics are the 305 except for the 2nd pic which is the 275 on the front.


Thanks!

Gallery updated with full car pics. Pics were taken before the tires were mounted though. When the weather gets a little better I will take some better ones.
Car Pics

I guess I should have read that last line of type, I was too quick to jump to your gallery, I'm like those don't look any different then the stock shoes :rofl2:

Sorry for the late reply, had to go racing this weekend :).

Yeah I would throw an 305 on a 10" rim, but thats for sure as wide as I would go. Also, do your research because some tires are wider than what they say on the sidewall. For example, Toyo R888 and R1R run 10mm wider than what they say on the sidewall.

Thanks for the pics... I'll await the upcoming pics that are pending nicer weather. Has the stance become dramatically more aggressive with the added contact patch or has the visual agressiveness been subdued due to the relatively limiting 10" width in the rear wheels?

Pardon my run-on sentence.

It is subtly more aggressive. My car buddy at work here didn't know I was getting the tires mounted. When I showed up at work that day he looked at my car and was trying to figure out what I changed. He said the car looked more aggressive but he couldn't figure out what was different. So I would say that it does make a visual change but it's not one that is going to jump out at you. The sun is out today so I should be able to snap some pics even if there is still sand everywhere.

Update:

I will be doing the 275F and 305R as well. I'm probably going with a 9.5 and 10.5 setup. I'll take pics as I receive everything within the next 3-4 weeks.

Would you please snap some shots of the rear view while capturing the bumper and lights for visual perspective?

Much grateful.

What are you getting for wheels Danny?

I took some yesterday but they didn't come out well in the full sun with a white car. It's a little more overcast today so I will try again.

Here you go:
Bridgestone RE-11's on stock sport wheels