rx-8 wheels: spacers and tires?

[intellibomb]

hello all,
i have been looking at the rx8 wheels .....
what size spacers do they need?
any reccomendations on tires from those with them on their svxs?
also, do teh rx8 lugs work?
thanks a bunch.

[BoxerFanatic]

There are several folks who have done that, and I'll let them answer the particulars, if any of this is not correct...

But I believe most mazda lugs and lug nuts (as well as many other brands) are 1.5mm thread pitch, and most Subarus/Nissans use 1.25mm thread pitch lugs and lug nuts.

The RX8 wheels, like most wheels, but NOT SVX OE wheels... use a conical shaped lug seat (a cone shape on the lug, and an similarly shaped inward cone on the wheel lug holes) which will require conical lug nuts, which the SVX sleeve-and-washer style lug nuts are not really compatible with.

Conical seat lug nuts from a Legacy or Impreza should work, as will any aftermarket lug nut with the correct thread pitch for the wheel studs. Wheels won't cross over from those other subarus because the studs are spaced differently, but the lugs are the same pitch, and most of the newer subarus have the conical seat style lugs.

McGard spline drives, or other brands of aftermarket lug nuts, (as long as they are well constructed) will work, as long as the seat style, and the thread pitch are right.

For tire sizes, I usually recommend checking out this tire size calculator, which will compare two sizes against each other. It is hosted and provided by Miata.net, a good Miata forum, but accepts any two tire sizes to compare, it isn't strictly tied to Miata fitments. (you might have to wait a bit for the java to properly load...)
http://www.miata.net/garage/tirecalc.html

Stock Tires/Wheels
7.5x16" 5 lug directional alloys, wheel Offset +55mm (2.17 inches)
215/55R16 all-season performance tires
P215/55R16

Using the above calculator... about the closest I could figure would be 235/40-18, which would be 1/10th of an inch larger in over-all rolling diameter, all else being equal. (different tire models and brands vary... the estimate is based on raw math ideals.)

Stock RX8 18" inch wheels are 8 inches wide, and have a 50mm offset, 5x114.3 bolt pattern, and 67.1 center bore hole

Very near to what SVX's width and offset are... so they should fit without spacers, but do need a center ring adapters, to have the load of the wheel supported by the center ring of the hub, which extends through the brake disc. That takes some of the shearing forces off of the lugs, by the wheel being supported directly to the hub itself.

A plastic spacer ring, rated for an 57.1 inner diameter, and RX8's 67.1 wheel hole diameter on it's outer edge (10mm thickness, basically), should finish that out nicely.

Just to be more particular about the offset... I use this other calculator:
http://www.1010tires.com/WheelOffsetCalculator.asp
The only numbers you need for offset are wheel width, and wheel offset. Wheel diameter makes little difference, and isn't calculated in the math.

Comparing a 7.5 inch wide OE SVX wheel with 55mm of offset, and an OE RX8 Wheel with 8 inch width, and 50mm offset, the calculator returns the following.
The inner wheel rim moves 1mm inboard (closer to the suspension... but that is a very small number.)
The outer wheel rim moves 11mm outboard (toward the fender edge, and tucks less, but SVX stock wheels have a MASSIVE tuck, so 11mm is probably not going to hurt a thing, and will probably look better.)

Ideally you want to stay as close to even as possible, but those numbers are pretty close, over-all, hence why RX8 wheels are fitted to SVXs around here.

Just on an interesting side note...
an optional RX8 wheel was actually offered in 16x7... not far off the SVX's OE wheel size... and it actually looks kind of nice. (although I would probably go with 17" wheels if I were to put anything non-OE on my SVX...)


I wonder if these would look good on my Claret/gray... I'd prefer to have the blue paint on my SVX, than even the wheels, though.

[Crazy_pilot]

^^^What he said. Have you tried this calculator? I prefer it to the Miata one, as it lets you input offset information for the wheel. It's also a lot nicer looking.