Tire Sizes for Street and Autocross SC

Miata Parts, Intakes, Superchargers, Headers, Exhausts, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.

Tire Sizes for Street and Autocross SC

Postby RobertR506 » Mon Dec 28, 2020 6:36 am

This Spring I’ll be getting new Summer tires for my 2017 MX-5 ND1 AT, most likely Conti ECS and 17x7 wheels. Which, do you think, would work better for spirited street driving and an occasional autocross SC, 205/45, 215/45, or 225/45? Also, what offset should I have for each size? Would there be any advantage going to a 16x7 wheel with 225/50s. I noticed that you have 225/45s on your SC car. Thanks.
Posts: 5
Joined: Thu Nov 12, 2020 5:50 am

Re: Tire Sizes for Street and Autocross SC

Postby Brian » Mon Dec 28, 2020 7:46 am

My wife's supercharged RF indeed has 16x8 and 225/50. That's to soften the street ride with the race valved Ohlins on that car.

For street use 215/15 on light 17x7 works great, plenty of performance and yet some curb rash protection for the wheels. The 225/45 on 17x7 is what we must use for SCCA autocross, feels a bit sloppy on just 7 inch wide wheel but if softer ride was the goal then that would get you that result, typically customers going 17x8 for 225/45. You can indeed push offset out a bit with the more conservative tire size choices, how much depends on variables like which tire, which size, how much negative camber.
Brian Goodwin
Good-Win Racing
Site Admin
Posts: 10345
Joined: Tue Feb 15, 2005 11:44 am
Location: San Diego CA

Return to Mazda Miata and Fiat 124

Who is online

Users browsing this forum: No registered users and 7 guests