Upgrade to Continentals?

JARblue

I don't know why I thought you had Nismo wheels. The OEM rear tire size for the sport wheels is 275/35/19. That is 26.6 inch diameter. So when calculating the speedo differentials, make sure that's the comparison you used and not the 26.9 Nismo diameter I cited earlier (I didn't bother to check your math). Edit- I checked your math and it looks off to me. Compare sizes 275/35/19 with whatever size you're looking at. The speed differential calculation is done for you on that website.

If you go 265/35/19 and 305/30/19, the tire diameter is reduced the same in the front and the rear (-1.5%) and gives you a 1 mph difference at 70 mph. Very reasonable.
If you use the 295/40/19 rear tires, the diameter increases by 1.9% which gives you a 1.3 mph difference at 70 mph. Still plenty reasonable.

Also, I like the benefit of going down in tire diameter makes you think you're going faster than you are, which helps me cut down on those speeding tickets lol. I've had cops tell me it's easy to recalibrate the speedometer, but I've never bothered to look into it.

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abm89

I'm going to go out on a limb and say they're talking out of their a$$. Anyone who's looked into the Z's electronics knows that most of the data is communicated over CAN, and likely requires the consult device.

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Complete Parts List:
https://github.com/abm89/ztouge-build

JARblue

The first time I heard that, in my head I was thinking, "yeah, maybe 50 years ago in the first car you got as a kid. Now only the dealer can do it and they'll charge an astronomical fee."

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