Another fitment question...

I have 17 X 9 +45s.

So I see from the wheel fitment guide that a 245 tire will fit on a wheel with +45 offset on stock suspension without rubbing. It is the widest tire for that offset that will fit without rubbing. My question is, if I am running a 255 tire but with UK suspension at -2 degrees of camber in the rear, will I need to roll? I have heard that quote passed around which says "for every degree of camber, you get 10mm more additional clearance" or something like that. I would prefer to not the rears.

 

I would say yest they are going to rub without modification. If you go with a 245/40R17 and run more negative camber you may get away without the fender lip roll.

 

Is it true about the 1 degree of camber = 10mm clearance? Someone verify this?

 

Here's a quick number. I took the tire radius and moved it by 1 degree using trig to get a number. Tire radius from the miata.net calculator is about 315mm. That number is halfway between the radius of a 245 40 17 and a 255 40 17 size tire.

Tire radius * sin(1deg) = offset
315mm * (0.0175) = 5.5mm

Since tires are symmetric, that 5.5mm translates to an actual tire width of 11mm. Sounds like the rule of thumb is reasonable.