Miata Wheel & Tire Fitment

Published: March 30, 2018

Terminology

*Flat roll means the inside edge of the fender is rolled upward, as close as possible to the fender. This moves the fender edge physically further away from the tire and and angles it such that if the tire does touch the fender, the contact will be on the fender lip rather than the very edge which would shave the sidewall like a razor blade.

Pull means the fender is pulled outward from the wheel well. This is in practice normally accomplished by pushing on the wheel of the fender rolling tool from the inside of the wheel well outward.

15x7

This is the standard Spec Miata wheel size. Popular offsets have changed over the years, from +38 to +25.

15x7+38, 205/50-15

This should fit any NA or NB Miata with no modifications.

15x7+25, "Standard" 205/50-15, NA

Fits with:

  • Flat fender roll, front and rear;
  • Good amount of camber (-3 degrees in front).

15x7+25, Hoosier 205/50-15, NA

Hoosiers being wider require a mild pull on the front to keep the tires away from fender edges under compression. Without a pull the outside front tire tends to contact the fender in bumpy corners at high lateral Gs.

15x8

Depending on the offset, 15x8 is an easy fitment on both NA and NB cars while also being fairly wide.

15x8+36, "Standard" 205/50-15

As far as I remember this combination fits stock NA and NB cars without modifications.

15x9

The standard offset for 15x9 wheels is +36, as popularized by 949racing. Standard tire size for these wheels is 225/45-15, though 245/40-15 Maxxis RC-1 are also an option.

+36 offset puts the wheel right in the middle between the fender and the front spring. A higher offset would result in 225 and higher width tires running into the spring.

15x9+36 And Front Springs

At full steering lock, 15x9+36 with "standard" 225/45-15 tires rub stock front springs. This is a very light rub and it only happens at full lock. In practice, this wheel is perfectly usable on an NB with stock suspension because it is extremely rare to be in a full lock situation (parallel parking comes to mind but that's about it).

I have not had rubbing with aftermarket Flyin Miata springs, and Xida springs which are even smaller do not rub as well.

Running 225 Hoosiers or 245/40-15 would make this rubbing worse, though it still would require significant steering angle which on Hoosiers shouldn't be necessary/happening.

15x9+36, "Standard" 225/45-15, NA

For full clearance:

  • All inside fender edges need to be flat rolled;
  • Front fenders require a light pull;
  • -3 degrees of front camber.

In this configuration the tires will clear fenders through the full range of motion. If the car is used for street driving only on reasonably flat ground it may be possible to get away without doing the pull on front fenders.

15x9+36, 225/45-15 Hoosiers Or "Standard" 245/40-15, NA

Hoosiers are wider than standard tires, and 245/40-15 are also wider than 225/45-15 as one would expect.

This fitment requires a moderate front fender pull. The rear should still clear with only a flat roll.

15x9+36, "Standard" 205/50-15, NA

I have not personally run this combination but my guess is it will clear with a flat roll only on all corners if there is enough front camber.

15x9+36 "Standard" 225/45-15, NB

This configuration fits with a flat roll. It should fit with a flat roll even on stock suspension with stock alignment adjustment range (i.e., about -1 degree of front camber).

15x9+36, 225/45-15 Hoosiers Or "Standard" 245/40-15, NB

A light pull on the front fender is likely required, along with decent camber.

15x9+36, "Standard" 225/50-15, NA

The taller 225/50-15 create some challenges.

I have not tried this combination in the front; based on my experiences with it on NB cars, I don't think it will work without major fender alterations.

In the rear this combination works with a flat roll and a light pull.

15x9+36, "Standard" 225/50-15, NB

NB have more room under the fenders than NA. In the front, this combination can work depending on the track. Even with a significant pull the outside front tire continued hitting the fender at VIR hog pen which is a downhill right hander with a compression point. On flat tracks the tire should work with:

  • Flat roll;
  • Moderate pull in the front;
  • Good camber (-3 degrees).

In the rear a flat roll and a light pull are needed.