Although the rear rim size didnt change until 88, I am searching for rear tires and getting warnings from major tire retailers indicating that the 87 GT requires different tire sizes between front and back. Is this correct or just a database error? So why would it matter to specifically have 205 front and 215 rear if the rim is supposed to be the same for 86-87 vs the 88?

http://home.xnet.com/~paulv/MajorSpecs.htm
15x7.0 in.
205/215-60R15

Tirerack size for 87:
Front: 205/60-15
Rear: 215/60-15

Its correct. The 86-87 requires 205 in front and 215 at the rear. That was this setup from the factory.

Many owners change wheels and install tire sizes of 16" and 17" but you've got to watch the width as the clearance for the tires can be tight It also depends on the offset of the wheels being used, If you want OEM size the tires specified above are the correct sizes but with 15" tires you can go slightly wider in the rear

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

If you look on the end of the driver's door there should be a label that gives the correct tire size for the car.... providing it hasn't been painted over or faded too much to read. What the guys said above is correct though.

I went up one size; 215/60-15 in front, and 225/60-15 in the rear, on the stock 15x7 GT rims. It gets a little bit more tire on the pavement, and it helps get rid of the 4x4 look somewhat, even if you don't lower it (I did that too). It clears the struts just fine in the back, and up front there are no rubbing issues unless you lower it, and even then only with new tires and at full lock. Speedometer error is not noticeable over the life of the tire.

I have Falken Ziex 512's from Discount Tire currently, but I've also used BFG Comp T/A HR4's. I've had this tire setup on mine since 1995.

I went to Firestone and bought two rear 215 x 15 tires. I decided to just stick to stock size and worry about it later. I'm assuming that a wider tire with a lower sidewall would help alleviate some of that fishtail feeling?

quote Originally posted by sricka01: I went to Firestone and bought two rear 215 x 15 tires. I decided to just stick to stock size and worry about it later. I'm assuming that a wider tire with a lower sidewall would help alleviate some of that fishtail feeling?

I only had that fishtail feeling twice. Once when I had the alignment totally screwed up (after replacing the struts, and having a rotten lower rear control arm bushing that I failed to notice), and the second time was with mismatched tire brands/speed ratings front and rear (may have just been a bad set of tires, but the problem went away when I swapped the old tires back on).

[This message has been edited by 2birds (edited 10-06-2008).]