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Philo · 09-06-2004, 06:13 PM

My '79 has 255/60-15's on the rear (stock is 225/70-15's, which are on the front). The car has 15X8 Snowflakes. The rears are worn out, and since 'ST' Goodyears are not longer available, it is time to get four new ones. I noticed that there is a height difference of (roughly) 2" between these two tire sizes. I would like to use tires with the stock circumference, to keep the speedo accurate. If I go with a wider (say 275/60-15) I am almost positive they will rub the fenders. If you have been down this road, please give me some advice.

I have been reading Mark T's post about snowflakes, but need more detailed info about sizes.

As a last question, can a couple of you go out to your '79 era TA's and measure from the floor to the fender lip at the wheel centerline so I can compare your car's height at that point with my car to see if my springs are too soft? Please give me your tire sizes too. The clearance looks about the same as the ones I have seen in pictures, but even an inch would make a lot of difference.

Thanks.

Philo · 09-06-2004, 06:13 PM

My '79 has 255/60-15's on the rear (stock is 225/70-15's, which are on the front). The car has 15X8 Snowflakes. The rears are worn out, and since 'ST' Goodyears are not longer available, it is time to get four new ones. I noticed that there is a height difference of (roughly) 2" between these two tire sizes. I would like to use tires with the stock circumference, to keep the speedo accurate. If I go with a wider (say 275/60-15) I am almost positive they will rub the fenders. If you have been down this road, please give me some advice.

I have been reading Mark T's post about snowflakes, but need more detailed info about sizes.

As a last question, can a couple of you go out to your '79 era TA's and measure from the floor to the fender lip at the wheel centerline so I can compare your car's height at that point with my car to see if my springs are too soft? Please give me your tire sizes too. The clearance looks about the same as the ones I have seen in pictures, but even an inch would make a lot of difference.

Thanks.

68ragtop · 09-06-2004, 06:59 PM

I think a lot of guys are running 255/60/15's with no problem, But I think anything wider than that becomes an issue, at least in the front. I have had a few different sizes on my T/A's, & like the 245/60/15's they are slightly wider, & a little lower profile than the factory WS6 tire size. Thats just my preference. I think most people on this board like the 255's, but might be running wider. I am pretty sure there are old topics covering this same issue if you run a search.

68ragtop

Brian Baker · 09-06-2004, 07:28 PM

BFG 245/60's were on my car when it was still street driven daily. On 15x8 rims. The tires are roughly 26" in diameter with a smidge over 8" of tread. They fit well and didn't screw with the speedometer reading.

MalteseFalcon · 09-06-2004, 08:12 PM

In the VSE Performance handbook, Herb Adam says that 255-60 15's are the upper limit without resorting to fender surgery. He says to get more room in the back, you can remove the rear seat belt anchors and hammer in the mounts, as well as cutting and bending up the fender lip. In the front, you can trim the outer edge of the wheelhouse off and bend up the fender lip.

Personally, I wouldn't cut up my car for the extra 20mm (3/4 inch) in tread width I might gain.

Larry Navarro · 09-07-2004, 08:50 AM

In my opinion, I think 275-60's look a little tall for a 2nd gen t/a.
Truck tire.

tata455 · 09-07-2004, 09:25 PM

The 255x60x15 will work great on the TA. They are virtually the same diameter as the stock Factory 225x70x15. Some Brands tread patterns look wider than others. BFGoodrich and Firestore are nice. The GoodYear GTII's look small. The BFGoodrich 245x60x15 are also very nice looking. 235x60x15 look nice on a lowered car or with Torque Thrust II's. Lastly, some folks run the 265x50x15 BFGoodrich. These are smaller in diameter, but have a wide profile look. All of the above combinations work with the stock 15x8 snowflakes. Only the 255's are the correct diameter. All the others are smaller and will impact the speedometer reading to some degree.

tata455 · 09-07-2004, 09:30 PM

Factory stock is 225x70x15. The 255x60x15 is virtually the same diameter. Speedo will work fine and they look great. 245x60x15 also look really nice, but are slightly smaller and won't fill the wheel well totally. Still a good choice though. Of course Speedo will be slightly off. 235x60x15's look nice on lowered cars and with Torque Thrust II 15x8.5 rims. Lastly some run the 265x50x15. They look nice and wide. Also, pay attention to the road surface width. The BFGoodrich and Firstone Firehawks have a nice wide look. Goodyear GTII's look skinny when compared in the same size. Feel free to email me with direct questions if you would like. tata455@aol.com

Gordy Doyle · 09-08-2004, 08:52 PM

Maltese Falcon when you mentioned Herb Adams book was he talking about any specific years of 2nd gen firebirds? Also when you mentioned trimming the wheelhouses can you go into more detail? Are you talking about the edge where the speed nuts mounts on the inner fender? And can you still attach the inner fender to the fender if you trim that area?
Thanks for the clarification
Gordy

Trev · 09-10-2004, 05:49 PM

255/60x15". The front of my car is lowered so I have a bit of a clearance issue over bumps. But this is as big as you can go generally without mods, and they are the right diameter compared to stock.

Gordy Doyle · 09-10-2004, 08:42 PM

Trev that looks sweet. What kind of clearance issues where's it rubbing?
Gordy

Trev · 09-10-2004, 09:00 PM

On bumps and hard turns, the front tires will rub under the fender lip. I could go the Herb Adams route and make clearance, but I think the downside of his modification is that you make a gap for road dirt to be sprayed up into the area over the inner fender. I think I will raise the front of the car a little before I cut anything. It will have to wait a while though as I have too many other projects in the works. Another Trans Am, my 64 Corvette and a large collection of Hurricanes to deal with!!!

Philo · 09-11-2004, 09:09 AM

Thanks, everyone, for your replies. I plan on going with four BFG Radial TA, size 255/60-15, based on your comments.

LouisianaGuy · 09-11-2004, 12:16 PM

running 275/60/15 BFG's on my 77ta and they look good. i dont know if the 77 is any diff in the rear than a 79 thoe, but they are pretty tall but i have no clearance issues.
Mike

MalteseFalcon · 09-12-2004, 09:53 PM

I think the 255-60's are a good choice. You won't need to trim the inner fenders if you are running 255-R60-15's, but the trimming Adams is talking about is off of the edge of the iner wheel well that bolts to the inner edge of the fender - you have to take that off so that you can bend the lip on the fender up (which is what gives you the additional clearance).

I tried to post a picture of this in one of the other posts, but its too large, even after trying to shrink it.

By the way, did you know that Camaro front wheel houses are smaller than Firebirds, and more prone to tire fitment problems?

Gordy Doyle · 09-12-2004, 09:58 PM

Steve according to Herb Adams when you trim the inner wheel well will you still be able to bolt it to the fender?
That's interesting about the camaro inner wheel wells being smaller. I'll have to look at my brother in law's car.
By the way is there any way you could email that pic to me at gordydoyle@sbcglobal.net
Thanks for your help
Gordy

Trev · 09-13-2004, 04:45 AM

When you trim the inner fender (Adams style), you lose at least 2 fixing bolts to the outer fender. The inner fenders do provide some rigidity to the front end, but you can still use the remaining bolt positions. Here is the info from the brochure.

Gordy Doyle · 09-13-2004, 07:08 AM

Trev thanks for that info. It looks like they took about 1/2 inch off at the top(?) and less at the bottom
Thanks again
Gordy

Skip Fix · 09-13-2004, 07:36 AM

My 275-60-15s always woul drub on hard bumps or turning up a steep incline rub on the inside. For the strip DOTs they are OK but for true street driving too tall.

Trev · 09-13-2004, 01:33 PM

Gordy, I think it is more like 3 inches at the top and blending out about 2/3 of the way down each side. Again, my biggest concern with this is how much road dirt would be allowed to build up between the inner and outer fender. Protecting the fender wells from dirt build up is a large part of what the inner fenders are for. If I do this on my car, I will replace the cut out metal with something that looks like a mini tub so as to fill the gap back in again.

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