Miata Wheel Question

What would be the proper offset and/or backspacing for a 15x7 wheel for a Miata?

Come on guys! An hour and no answer to this seemingly no brainer question? I thought I'd have an answer within 5 minutes. Guess you guys don't know as much about Miata's as you want the rest of us to think.

It depends on which tires you want to run and what year miata, and the suspension you want to run and if you are willing to roll the fenders.

For a stockish miata with a 195/50 or 205/50, 35-40mm works great.

In reply to mw:

Is that offset or backspacing?

No direct experience (stock wheels on my Miata), but what I've read says to stay close to the stock offset of +40.

Search miataforum.com or clubroadster.net for plenty of information.

A 35-40mm backspace would be a bit odd, that's offset :)

The "proper" offset is +40-45.

Spec Miatas use +30mm, and you can run that on just about any Miata. There are some good, affordable wheels designed for Specs in the 15x7 size, such as the TR Motorsports C1 for $99.

Keith wrote: A 35-40mm backspace would be a bit odd, that's offset :)

I'm a Honda guy.

I run 43mm offset 15x7 Volk TE-37. Work well with a little fender rolling.

bravenrace wrote:

Keith wrote: A 35-40mm backspace would be a bit odd, that's offset :)

I'm a Honda guy.

I think it's what Hondas use too actually.

Clay, you need to roll fenders with a +43 15x7? What size tires are you running? There shouldn't be any interference with that. It's basically stock.

IIRC 27-48 is the range depending on tire section width and ride height. I'll bet most people buy 35-38.

The fender rolling wasn't required. It was more of a precaution due to the lowering of the Konis, but figured I would share in the interest of full disclosure. In fact, I scrub a bit on the inner fender liner on the outside front tire in hard turns, but none on the fender lip. I'm running 205/50r15 Azenis 615's.

I can also add this exact set of wheels and tires fit my 89 Civic Si perfectly as well. It's nice to have an interchangable set of wheels and tires. I bought them from a guy who had them on his 200SX SE-R, but he used spacers.

And remember a 7" wheel with the same depth backside setting would have a different "mm offset" than a 6.5" or a 7.5" wheel.

A 15x6" wheel might need a +30mm whereas a 15x8" wheel would be a +45 or +50mm.

Backside setting is measured from hub face to inner wheel lip where offset is the measurement of how far from wheel center the hub flange is.

BTW, Here are some pics of these wheels on my Miata and my old Civic.

Clay wrote: The fender rolling wasn't required. It was more of a precaution due to the lowering of the Konis, but figured I would share in the interest of full disclosure. In fact, I scrub a bit on the inner fender liner on the outside front tire in hard turns, but none on the fender lip. I'm running 205/50r15 Azenis 615's.

Lowering the car doesn't make you rub, as the overall range of motion of the wheels doesn't change. It might make you rub more often, but it won't create rubbing where none previously existed.

If you do change that range of motion (such as, oh, installing shocks with a shorter body such as the rear Konis in a Miata) then you may introduce rubbing. Same with running larger diameter tires such as the 205/50-15 instead of the original diameter 195/50-15 for a Miata.

Just FYI. Nice wheels!

Backspacing is useful if you're concerned about clearance, but offset is what you need if you're interested in suspension geometry. You can calculate one from the other if you know the wheel width.