I want to get some 10 inch wide rims, but all the ones I have found are alot larger than stock, I have 15s right now and the ones Im finding are 18-20s. My stepdad had an 85 Firebird and he said that when he put 18s on with a smaller height tire to match the original ride height, that it handled much worse than with the stock rims and tires. I just need some other opinions.

 

Why 10" wide? What size tires do you want to run? What rim size are you looking at 15, 16, 17? I don't understand how your stepdad's car ran worse with bigger rim/tire combo. How? Was it that he felt every bump because he had lower profile tires?

You can put a 285 40 17 on a 9.5" wide rim. Do you want bigger?

What rim size is your preference or do you have one?

 

he said that he couldnt feel what it was doing, like at higher speeds he couldnt tell when it was ready to slide. I want right now Im running 255/65/15s I want to run wider rims/tires, whatever is closest to 10 inches wide, I wouldnt mind running 16s but Id like to stay with 15s, for speedometer accuracy.

 

Chanding the speedo gear is quite simple and inexpensive but you can run 17's while still maintaining a fair sized side wall and stock tire height ( which would keep your speedo accurate). The story your dad told you about big rims = bad handling does NOT check out. Why would everyone in the world run lower profile tires for handling if that were the case??
Run some 17x9.5 wide rims with 5.5" backspace with 275/40/17s
and 17x8 with 4.5"bs with 255/45/17s ; take your dad for rip and I guarantee he changes his mind

PS if you want you could run a 10" wide rim with 5.75" of backspace

 

If you keep the tire height close to the original height of 26" then the speedo will not be out. 17" will give a crisper ride than 15". You can put a 275 50 15 on an 8" rim. If you want a bigger combo, changing the speedo gear is easy and fairly inexpensive. There are threads on the right speedo gear change. Personally I would go with a 17" setup go what camarojustin suggests. It will fit well and the bs sizes are fairly common on a lot of rims.

 

Ok I just found some rims I like, How much backspacing would I need to fit an 11inch? Or would it be a bad idea to go with 11s all around?

heres the link
http://www.rims-n-tires.com/rt_wheel...roit&model=ZR1

 

Ok don't really do mm offset. The MOST you can go is a 6" bs. The front of the rim might stick out a bit from the fender. There are posts and pics of guys with 10" rims and 6" bs. Do a search to see how their rims fit the wheel well and that will give you a good idea. Remember your rims will stick out an addional 1 inch.

 

Ok Ive hear I can fit 1s in the back with correct backspacing, and 9.5s in the front. And have them not stick out.

 

First, decide on a tire size that fits your goals, then buy rims that the tires are designed for. Also, the rims must have the correct back spacing to fit the 3rd gen cars. The wheels that you have in the link above fit the 4th gen cars. Those wheels are wrong for your car.

As stated above, you could run the P275/40R17s on 17x9.5" wheels OR run P245/45R17s on 17x8.0" wheels. The 17x8.0 wheels can be purchased at SLP as a direct fit for 3rd gen cars, no spacers needed.

 

You will be modifying your car or have the rim stick outside of the fender with an 11 inch rim

10 inches MAX ! and find the ones with the right backspacing ( You could run adapters if you really want 4th Gen or Vette rims )

 

I think Im just gonna go with the firehawk wheels

http://www.hawksthirdgenparts.com/in...ROD&ProdID=479

 

Good choice. On a 9.5" rim you can run a 255 45, 275 40 or 285 40.