Help, tire size question

venturi

Yes, I've used the search tool to death, as well as google
But now I'm just confused


I am putting forged COR monoblocks on my Nissan 370z 2012 roadster sport touring, which comes originally with Bridgestone potenza and 19" Rays, 19x9F and 19x10R.

I'm putting on COR rims:
20x9 front
20x11 rear

In trying to find the right tire and tire size I've gone nuts!

Prerequisite data:
1. In moving from "19 to "20 tire, I want to preserve the exact rolling diameter, which from research is between 26.5 and 26.2 on the 19" rays and BR Potenza the car comes with.
I want to preserve the size and geometry so that speedo and other factors are minimized and not impacted.
2. I also don't want to sacrifice too much comfort which can easily be done in moving to a 20" rim and the wrong tire, from a 19" rim.
3. I don't want tire mobility and steering rotation to rub or impact any structures in the wheel well.
4. I want the tire to look correct on rim so that it doesn't squish out or look tucked in, but proportionally correct to the rim.


The rep at COR for my wheels suggested these tire sizes:

245/35/20 fronts /// Either 285/30/20 *or 295/30/20 *For the rear

My problem is this (1)
The 285/30/20 by Nitto, BR, and Pirelli is only approved to "10.5 rims, not "11 rims,
The 295/30/20 looked to have better official fitment specs to a 20x11 rim.
Some wheel manufacturers even went as high as a 305 on the 11rim

----So it sounds like 295/30-20 is correct for the rear.----


However:


(2)
The front, every monoblock wheel firm on the suggested tire recommends the 255/35-20 for the 20x9 wheel on their sites, but the COR rep suggest a 245/35-20


So...
With my pre requisites, what do I buy for tires. I don't go to the track, this is more sport and comfort and aesthetics to me.

So what tire size and recommended brand?



Thank you for any help, I've learned in this forum that it pays to be specific

Thank you

COR F1 Forma Monoblock Wheels | Competition Series

XwChriswX

Michelin Pilot Super Sports ftw.

Sizes: 20"

275/30ZR20 XL 97Y B
275/35ZR20 XL 102Y B
285/25ZR20XL 93Y B
285/30ZR20XL99Y FER
285/30ZR20 XL 99Y B
315/35ZR20XL110Y FER

I love my set, not on 20's, but still a great tire.

__________________

Bonnie - Stage 2, Audio build coming this fall!
R.I.P. Abby 3/29/10 - 3/30/14

venturi

Sorry, probably my lack of knowledge, but I'm confused by your reply.
Are those sizes for rear wheel? Will they protrude or retract from edge of wheel? Circumference still needs to be the same as stock, thx

XwChriswX

Circumference will be the same, and only slightly off if you chose a different side profile. But the Width doesn't affect the circumference.

The diameter of the wheel is 20" The width of the wheel will be somewhere between 9-12".

If you don't want the sidewall of the tire to extend past the face of the wheel, then take the width of your wheel and do a standard to metric conversion to find out the closest width in mm's. Then get that width of tire.

Does that help?

__________________

Bonnie - Stage 2, Audio build coming this fall!
R.I.P. Abby 3/29/10 - 3/30/14

daisuke149

man you are no help at all... lol.

for the front wheel, 245/35/20 is 0.1% different from your OEM. Aka its about a perfect fit.

the rear is where you will run into problems.

your best bet is the 295/30/20. which is 1.5% larger than your OEM. If you go 305/30/20 which you could, it would be 2.3% larger. if you got 305/25/20 you would be 2.2% smaller.

XwChriswX

Which is exactly what I said?

__________________

Bonnie - Stage 2, Audio build coming this fall!
R.I.P. Abby 3/29/10 - 3/30/14

daisuke149

you suggested a 315/35/20...

also wheel width is measured from where the tire bead sits..

there is a lil lip that extends out of that

an 11" wide wheel, generally measuged from 11.8 to 12.2" wide from edge to edge.

which is why a 305 tire, aka 12.2" wide looks good on them.

XwChriswX

I gave a listing of all the 20" tires available for that brand/model tire. I didn't say 'this is the best'.

__________________

Bonnie - Stage 2, Audio build coming this fall!
R.I.P. Abby 3/29/10 - 3/30/14

venturi

Thank you,
I'm going to go with the 255/35-20 front and the 295/30-20 rear. I dug and dug and found that the 245/front will look visually different compared to the rear if I went with 295 rear.

The diameter on 255/35-20 is 26.73 and will have the same "protrusion and depth" as the 295 rear.

NOW... the next question is obvious..

What brand tire? Nitto, BR, Pirelli, Falk, etc??
( the critaria (1):must be able to rotate the rears and then rotate the fronts. Non asymmetrical recommendations. (2) comfort and sportiness - moving from 19 to 20 can make for a ruff ride, the right tire can minimize that.
(3) Road noise - after all it is a roadster, lesser is better

Although I'm sure my exhaust choice will play a greater roll for noise in the opposite direction - Tanabe cat back and their Y-pipe, but some tires have "excessive" road noise

Waiz

255-30-20 = 26.02" overall diameter

295-30-20 = 26.96" overall diameter

Looks good to me and maintains enough stagger to keep VDC happy

XwChriswX

I will say from experience, having a 255/295 setup will not be the best in the rain. You'll want a wider front, at least 265 if not 275.

__________________

Bonnie - Stage 2, Audio build coming this fall!
R.I.P. Abby 3/29/10 - 3/30/14

venturi

Would a 275 on a 9" rim have firmest issues in the front well, steering clearance?
Would there an obvious visual difference as compared to the 255?

I had settled into a Pirelli zero set but had not pulled the trigger

20x9F with pzero 255/35ZR20XL with dia 27.0 and 10 deep tread
20x11R with pzero 295/30ZR20XL with dia 26.96 and 10 deep tread

After crunching through specs forever, I'm kinda numb but would there be a better set up?