AMGY

Using this calculator it seems these tire sizes are compatible. Am I right? Will I have TC issues?

285/30/19 Diameter 25.7

235/35/19 Diameter 25.5

http://www.miata.net/garage/tirecalc.html

dynomite05

You will probably have issues with the 285 in the rear.

AMGY

How so? Rubbing or diameter?

Klinh

225-45-17 stock to 235-35-19 is about 2% different. 245-45-17 to 285-30-19 is about 4%. 4% different is not a good thing and might effect the odometer, ABS, ESP, traction control...etc. General rules, as long as you stay within 3% compared to stock size. The other issue with 285 tire is rubbing and that's a warrantee. I barely got away with 265-30-19 tires.

Kevwood

The previous owner of my car had 275/30-19's on the rear and they rubbed going over almost every bump. I now have 265's and have a very, very slight rub while blasting through corners on the roadcourse but nothing on the street.

dr_npz

+1 Go with 265/30 R19. One other thing is that every manufacturer has different tires. Even with the same tire size, some are bigger, some smaller.