Just a quick blog on wheel and tire sizes for the SA22C chassis.  I talked previously about how stock car tires were too tall, and after a little internet searching, I found the original tire sizes from 1979.

I am going to attempt to paste this in as a table.  Please be patient, my computer skills aren’t the best.

Hopefully that displays OK for most readers.  Please note, that these are calculated values except for the last tire.  The actual dimensions could vary by brand.  Dimensions are inches

I think that an inch taller than OE will be easy to accommodate.  The rear wheel wells are quite large, and I have removed much of the front wells in the SLA conversion process.  The 245/45-15 is borderline in that regard.  Since the Mongrel will be lower than factory, this makes things even more difficult.

This post was really just to give some background on the tire selection process which I had neglected to elaborate on before showing pictures of the tires I chose.

If you have any questions or comments, please use the form below.

Unfortunately, the good camera is broken, so I have had to go to the older unit which gives lower quality pictures.   Until the better one is returned from being repaired, images may not be as clear.

I have gone back-and-forth over my wheel and tire choice more times than I can count.  It really is one of the most critical decisions to be made on any car project.  Just think of all the things that are impacted by wheel and tire choice.

• Brake rotor size
• Brake caliper offset
• Scrub radius
• Fender clearance
• Suspension arm clearance
• Axle width
• Hub bolt pattern
• Hub center diameter
• Wheel stud size
• Ride height
• Gear ratio

And I am sure there are more.  I have read of builds that started with the wheel and tire combination and built almost everything else around that.

In my case, once I determined that I would do an SLA front suspension using stockcar parts, it was quite obvious that I would be using stockcar wheels.  Yes, it is possible to get some custom made wheels that would have allowed me to have any width, offset and diameter I might desire, but they are very expensive.  Not only that, but I have tried to avoid custom parts in this project since it will get hard use, and especially for something like a wheel which is easily damaged, I don’t want to deal with the replacement headaches associated with one-off parts.

Stockcar wheels are 15″ in diameter and made of steel.  The widths are between eight and ten inches.  I found a good deal on some 9½” wide units with a five inch backspace, and picked up eight of them.  They even came with the obligatory stickers and markings that are part of every stockcar takeoff part.

With wheels decided, it was on to tires.  This was much more complex than I originally thought.  The main difficultly stems from the fact that high performance street and road race tire manufacturers have abandoned the 15″ wheel for larger sizes.  The natural response is to fit stockcar wheels with stockcar tires.  While there are some that are suitable for actions other than turning left, they are all very tall.  The RX-7 was designed around a tire that is less than 23″ tall, so a fitting a 26″ tall stockcar tire is not easy.

So I went with cheap and easy to find knowing full well that tires wear out, so this didn’t need to be the last word on the situation.  I found Hoosier 225/45-15 R6 tires and had them mounted up.

Yes, you can fit 225 width tires on 9½” wide rims, even with a 45 series sidewall.

Inner tire clearance shouldn’t be a problem even if I go to the 275 width; the largest currently available for the 15″ wheel size.  The outer edge is a different story.

Time for those previous thoughts about fender flares to become more serious.