Hey guys, I've been looking into stock tire sizes and took a look at my car which is a 1984 Firebird SE with a 305 and I don't really know what to make of it. Here are my sizes.
Front
215/60/14
Rear
245/60/14

So obviously the front and rear tires are significantly different. I always see 15" and 16" tires mentioned but I have 14". I was wondering what effect having completely different tire sizes on the front and back can have and what effect the tires sizes listed here would have on my speedometer, RPM gauge, and driving characteristics? Assuming my RPM gauge is correct which I'm not sure about, I've always found that my car runs and shifts at very high RPMs. I've been told that it is due to the rear gear ratio but could these tires also be affecting the driving characteristics?

 

I thought Firebird SEs all came with 15" wheels from the factory...

245-60-14 is about the same overall diameter as a 245-50-16, which is 25.7" tall. 215-60-14 is about 24" tall, almost 2" shorter than the rears...

I had 205-70-14 tires on my Camaro when I bought it (was factory size).

 

I think these tires were put on by the previous owner, I doubt that they're factory sized. I've also found out the hard way that the previous owner didn't have a clue about what he was doing with this car. I forgot to ask what the stock tire size for a 84 Firebird SE was, does anybody know?

 

Tirerack says 235-60-15 size for the 15" wheels, weird considering the 84z was using 215-65-15.

 

Those aren't the stock size tires for your car. The factory didn't mix tire sizes. If they were 14's on the car from the factory, it would be like a 205/70/14. If 15's were on the car from the factory, I would say it should be a 215/65/15. If you still have the sticker on the driver door, it should list the factory tire size.

 

I do have stickers on the drivers side door but the really strange thing is that all the information has been blacked out. I just found out that my rims are called N89 turbo cast rims.

 

I'm in the same boat, the 'maro I just bought a couple weeks ago came with new 235/60s on 14x7s up front, and worn 215/70s on 14x8s on the rear. My short-term fix was to put the 235s on the 8s, and buy new 205/70s for the front. Looks a bit less stupid now, but the wheels are chromed 1970s junk, and the wheel arches look rather empty. In my case, I figure if I'm gonna buy wheels, I may as well go at least 17 inch for affordable tires like 245 /45 at a minimum.

 

Cosmik,

If you do go to 17" (smart idea btw), go for a 275-40-17 tire on a 9.5" wheel. The cost of tires is not so much higher than the 245-45, but there is a big jump in handling, braking, and straight line traction with the 275s.

Check these wheels out: http://www.ctw-motorsports.com