Mazda Talk Forums

Hello everyone,

I have a wheel question regarding wheel fitment on my 2006 MX-5. I hope someone here can help me.

I'm contemplating buying Volk Racing CE28N in 17 X 7.5. I have a choice of two offsets: 43 & 50. I plan on using a 215 X 45 X 17 tire. I don't believe I have seen an NC with this particular wheel. For all I know, it may not fit. BTW, the car isn't lowered (too many potholes and high curbs).

I'd like to use a 43 offset for appearance. With the smaller numerical offset, the wheel has a more attractive look due to being more dished in (compared to a 50 offset). If I changed the offset of the stock wheel to 43, the edge of the wheel would move out 12mm. However, the new wheel is 12.7 mm wider, so I not exactly sure how the interplay of these numbers will affect the fitment issue. Incidentally, the tire will be 10mm wider.

I did run across this wheel offset calculator:

http://74.125.95.132/search?q=cache:2QM ... cd=1&gl=us

According to it, the outside edge of the wheel will stick out 18mm more, and the inner clearance will increase by 6mm. If I'm interpreting the first number correctly, it makes sense by adding 12mm, the change in the edge of the wheel, to 6mm or half of the rim increase in thickness. Also the second number makes sense since the wheel is moved out 12 mm while being increase in thickness by 12mm resulting in 6mm more inner clearance.

However, with all of this, I can't answer my own question. I guess experience is the best answer. BTW, I have asked several wheel vendors in LA all with different answers!

Thanks,

WCS

Both offsets are going to fit. The 43mm will likely require slight fender lip roll...particularly in the rear.

Thanks for the info.

I made a cardboard template using the numbers from the offset program. It's was placed against the face of the wheel and shows where the edge of the new rim will be in relation to the fender. Sure enough a 43 offset is going to require modifying or rolling the fender.

I don't want to do any bodywork to the car, so it's a 50 offset.

WCS

Brian, on the fitment topic (once again) 17x8 et 48mm and a 235/40/17 tire fits with no need to roll correct? How about a 45mm offset on an 8" wide wheel? And to go in the opposite direction, a 53mm offset on an 8" wheel wouldn't be banging against any control arms or anything would it?

I recently installed Enkei RP03 I bought from Brian, 17x8 ET 48 and they fit fine on my stock-suspended '07. Call me a curmudgeon, but I don't understand why people still question this fitment considering all the posts here and on Miata.net that prove it works.

caoboy wrote:Brian, on the fitment topic (once again) 17x8 et 48mm and a 235/40/17 tire fits with no need to roll correct? How about a 45mm offset on an 8" wide wheel? And to go in the opposite direction, a 53mm offset on an 8" wheel wouldn't be banging against any control arms or anything would it?

Yes, the 235/40/17 fits at 48mm with no rolling needed for a STREET TIRE....but this answer may not apply to various oversized "race" tire choices like our R888. The 45mm will rub. As for going other direction, I have not done any fitment higher than 50mm....so I just can't say.

I have 245/40/17 on stock 17'' wheel's with no rolling needed too...