HELP~All squared setups please post here!
I must say, in browsing 60 pages of wheel/tire setups, I was pretty surprised to not find a single example of 19x8.5 wheels with 255/40-19 tires. It seems that most folks here have chosen to stretch narrow tires onto wide wheels. 
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Joined: May 2017
Posts: 559
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From: Charlotte, NC
I have 255/40 on 9.5s... I wish I had gone with 8.5s. I would recommend doing that... just make sure you have a nice offset. 8.5 at +20-25 lowered is about ideal IMO.
I just spent some time discussing the matter with a guy at TireRack and he could guarantee fitment of the 19x8.5 (45mm offset) wheels I was looking at with a 245/40-19 tire, but NOT the 255/40-19 tire that I would really prefer. He stated that the rears would be no problem, but I may rub up front at full lock. I'm thinking I may need to get the car in the air and take some measurements if nobody has ever attempted this . . . or just go for it and add spacers up front if it's a problem.
Last edited by Bionicman; Nov 3, 2017 at 12:04 PM.
Registered User
Joined: May 2017
Posts: 559
Likes: 48
From: Charlotte, NC
I am running 19x9.5 with +25 in front (to clear BBK with spacers) and +35 out back. I am pretty low as well. It looked like it was going to rub but it didn't with stock camber out front and back. The wheels did poke out a good bit in front, but if you go with 8.5s at the same offset it will be just about perfect. And 255s will give you some curb protection.
Here's one of the best fitments IMO, a 9.5 +40 on 255s all around
https://www.myg37.com/forums/g37-sed...ml#post4164814
https://www.myg37.com/forums/g37-sed...ml#post4164814
Here's one of the best fitments IMO, a 9.5 +40 on 255s all around
https://www.myg37.com/forums/g37-sed...ml#post4164814
https://www.myg37.com/forums/g37-sed...ml#post4164814
If you want to run 265s a 265/40 would be 2.3% taller and the 265/35 1.57% shorter, so those would work out quite a bit better as far as that diameter discrepancy.
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Joined: May 2007
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6spd, welcome to the site!
Going to be a tough fit, the 10+38 in front will have very little room at the upper bend of the spindle. My 18x9.5 +38s have a bit more than a 1/4" clearance at that point, so you'd be right at it w/ the 10s. If they were 19s or 20s it would be a bit easier as that bend in the spindle gets further out as you get larger in wheel diameter. And 275s in front might need to have the front fender edge flat-rolled like the rear. You rear wheel won't be a problem at all though.
Check our site calculator, it's simple but accurate~the 18x7.5 +45 vs. the 18x10 +38 will result in 24.75mm more to the inside and 38.75mm out.
https://www.myg37.com/forums/tire_rim_calculator.php
Going to be a tough fit, the 10+38 in front will have very little room at the upper bend of the spindle. My 18x9.5 +38s have a bit more than a 1/4" clearance at that point, so you'd be right at it w/ the 10s. If they were 19s or 20s it would be a bit easier as that bend in the spindle gets further out as you get larger in wheel diameter. And 275s in front might need to have the front fender edge flat-rolled like the rear. You rear wheel won't be a problem at all though.
Check our site calculator, it's simple but accurate~the 18x7.5 +45 vs. the 18x10 +38 will result in 24.75mm more to the inside and 38.75mm out.
https://www.myg37.com/forums/tire_rim_calculator.php
Enkei NT03RR, 18x10+38 square. 19.4 pounds each.
Bridgestone Potenza RE-71Rs, 275/35-18
Project Kics R40 Neo-Chrome lugnuts.
I did wind up running a 5mm spacer up front, because the spokes touched the caliper. I am VERY happy with the setup, the lightness, and the new grip. These will be for race purposes only...
