ncmail

i have an 87 Firebird V6. will these rims fit with no modification?? and if so what is the largest tires i can run with out modification? http://www.summitracing.com/parts/CRR-3985834/

ziggy89

look like they should fit might stick out a little. the 16x8 wheels have a 4.5" backspacing

Ron U.S.M.C.

I have 15 in. by 8in. rear wheels with 3.75 BS and 295/50r15 tires. They do not tuck into the wheel wells.The wheel in that link is a 4.0 BS. 1/4 In. difference. Here's a photo of what I'm talking about. I'm sorry that I do not have a complete answer to your question. But this is basically what you will get if you try to run that wheel with that BS and wide tires like in the photo. ( By the way Im working on getting my new rear wheels with new BS )

ncmail

do you have enough clearance to squeeze an extra 1/4" of backspaceing before you would rub??

Ron U.S.M.C.

The answer is yes . The problem is really not the 4.0 BS (You can go deeper) but the outside rim of a 4.0 bs 15 by 8in. wheel ,and tire sizes . Just got back from a tire and wheel shop and they actually let me try out wheel and tire combos with different BS. (They had a large selection of used wheels and tires ). The only ones they did not have were the ones I wanted to test out. . After considerable amount of measuring ,etc. We came to the conclusion that the 295/50r15 tire on a 15 by 10in. wheel with 5.5 BS is out of the question with out allot of work.(Thats the setup I was shooting for).So... They put a 255/60r15 on a 15 by 8in. wheel with 3.75 BS.(Outlaw 2 wheel) Thats the same size as what my rears are but with the thinner tire. They actually fit under the well. The bulge was level with the flair and the tread was slightly tucked under the well. So if you went with a 4.0 bs and the 255/60r15 you would still be at the very edge of the well and flare. Most of the guys I have talked to would still consider that to close. Now if you went with even a thinner tire that would bring it in even further. 4.5 bs on a 255/60r15 appears to be the ticket.( I understand you can get that BS with the wheel you chose but in a 16in. wheel ). Personally after running a 295/50 the 255/60 looks tiny to me. I'm going to hold out on doing anything until I look into pounding or cutting out the inner well. Others here may have a different opinion on what I just said. I'm just going buy what I saw today.

ncmail

so i should be fine with wat i am gonna be running then if i understand everything correctly i was planning on running a 275 or a 255 tire so you dont think i would have any rub? and should i go with a 60 profile when running a 15inch rim?

rims and tires are always something that got me all flustered haha

Ron U.S.M.C.

First off I must tell you that im trying to find a wheel and tire combo. for my car and am having a hard time of it also. I don't want to give you the wrong info. And have you buying wheels that are not going fit under and within the well with the wider tire with out rubbing. When I posted my last message I did it with the knowledge learned that day. So I was trying to put down what we did and some of the results. A lot of times someone with much greater knowledge will jump in and make corrections for something missed or measured wrong. Search and find someone that really knows tires and wheels. I would hate to see you make the same mistake I made. ( not enough BS to run a fatter tire and keep it “under”and "in" the well

Stephen

iTrader: (12)

In the stock 16" crosslaces, the fronts had 4.25" bs, the rears had 4.9" bs (call it 5"bs).

You should be safe up to about 5.5" bs. Cut the bumpstop back & you'll gain about another .75", for 6.25". Getting the another .75" that I have now, took a bit more work, but was well worth it to get a 11" wheel, well under my fenders!

ncmail

alright thank you the factory firebird rims are 7" wide with a 4" bs correct??

Stephen

iTrader: (12)

WHICH Firebird wheels There is a crosslace 15"' & 16", some other 15" wheels, some other 16"' wheels as well as several other Firebird wheels.

Got a pic? What size tires are currently on the car?

ncmail

mine are not the crosslace. if they were i would be leaving them on. i have the 15" rims that say pontiac on them they were also common on the Fieros