defdans, I've been through what you're going through already, here are all of your answers:

1. Tirerack is just covering their a$$. If you buy two tires, they give you this bull$hit advice that if the tires aren't all the same, you won't be able to control the car because the front and rear won't have the exact same handling/traction properties. They're basically telling you that you will get into an accident and kill yourself and they don't want your family to sue them. Ignore that crap and just get the tires you want.

2. You need to get 235/50/17s, not 235/55/17s for the rear. 235/55s will be too tall.

3. 235s in the rear will not cause any drivability problems, they fit just fine. However, if you do it, you won't be able to rotate your tires. While this is not the worst thing in the world, it's nice to be able to swap front to rear and vice versa, so the rears don't wear out so quickly. You could go for some cheap 215/55s for the rear, then get some really nice 235/50s later on when all 4 are worn out.

FYI, I have Goodyear Eagle F1 GS/D3s on all 4 (235/50/17), and I love these tires.

Edit: your rims aren't the stock RWD rims (someone mentioned that they look like they're AWD rims)... did you buy the car like that?

 

You had better make very sure that 235/50R17 are exactly the same height as the 215/55R17 because if they're off by .5" or more, the VDC is going to go bonkers.

 

Positive, the difference in circumference is only 0.2", and the diameters match at 26.3". I've been using the tire calculator at miata.net that I found on maxima.org waaaaaaay back in the day... I think you actually might have linked it Dave.

Miata.net tire size calculator

 

Thanks for all the advice, everybody.

Yes, these rims were on the car when I bought it. I bought the car used with about 30k miles.

I do have the original sticker that came with the car and it lists:

"Chrome Wheels (Set of 5) $1,600.00 (replaces standard wheels)"

as one of the options. That help at all?

 

^yup!

Those were the optional chrome rims that came on some of the G35X (4wd) sedans. they are quite rare!

 

Ah....I thought they were unique because I have never seen another G35 with these rims.

Apparently they came on some of the RWD sedans as well? Because mine's definitely not AWD. heh.

 

Cool, looks like the dealer swapped them in and upcharged the original buyer quite a bit! Lucky for you it probably didn't affect the price you paid very much. It'll look really sweet after you lower the car with some sport springs.

Did you order some tires yet?

 

Yeah, I actually ordered them and had them installed towards the end of June. I just got two Yoko S Drives in the original size.

I wish I had seen your posts before I ordered, as i would have gotten the 235s you suggested, but oh well.

Overall, I am very happy with the tires though.

Any guesses on how much it would cost to have it lowered? Never done that before...any negatives to getting it lowered?

 

I'm no expert on lowering, I installed my Eibach Pro-kit springs myself, so my cost was ~$250 for the springs. Complications include extreme negative camber leading to excessive tire wear. I believe if you lower the car with less aggressive springs like those from the coupe or the Z you won't run into the same problems, but I don't know anything about that first-hand. Check out the suspension forum for more info.