1981 Camaro Z28

[MP81]

All right, Radial TA it is.
[MENTION=757]TSTONE[/MENTION] [MENTION=470]81DaytonaPaceCar[/MENTION] [MENTION=558]9T8W66[/MENTION] (and anyone else with 2nd gen experience):

Should a 255/60R15 fit without issue

[TSTONE]

All right, Radial TA it is.
@TSTONE @81DaytonaPaceCar @9T8W66 (and anyone else with 2nd gen experience):

Should a 255/60R15 fit without issue

Std size for 81 was 235/60/15 so a 255 should fit just a slightly taller (.9)/wider (.7) profile. A lot of it has to due with how much the suspension is sagging. To be honest I don't remember off the top of mid what size mine are?

[MP81]

235/60? Was that for Camaros and Trans Ams?

Mine calls for 225/70R15s standard (with the optional N90s I have). I know a 255/60 is a closer diameter to than a 235/60 - but I can get them in either size, so that's good. I'll just likely need a speedo correction box or to change the gears to correct the speedometer.

[81DaytonaPaceCar]

I currently run 255/60s on the '81 on stock 8" wide wheels with no spacers. The only possible issue is clearance to the rear shock tower area is very, very tight...maybe 5-7 mm. You can't get your finger in between the tire and the sheetmetal...

235/60? Was that for Camaros and Trans Ams?

Mine calls for 225/70R15s standard (with the optional N90s I have). I know a 255/60 is a closer diameter to than a 235/60 - but I can get them in either size, so that's good. I'll just likely need a speedo correction box or to change the gears to correct the speedometer.

Honestly, I really wouldn't worry about it. These things weren't accurate when new, and they surely didn't improve with age. I read somewhere years ago that when, back in the day, police departments "certified" their cruiser's speedos, the acceptable range was +/- 2 mph. The difference between a 235/70 and a 255/60 is only 4.5 mm anyway, so it's unlikely you could correct it even if you had to...

[MP81]

I currently run 255/60s on the '81 on stock 8" wide wheels with no spacers. The only possible issue is clearance to the rear shock tower area is very, very tight...maybe 5-7 mm. You can't get your finger in between the tire and the sheetmetal...



Honestly, I really wouldn't worry about it. These things weren't accurate when new, and they surely didn't improve with age. I read somewhere years ago that when, back in the day, police departments "certified" their cruiser's speedos, the acceptable range was +/- 2 mph. The difference between a 235/70 and a 255/60 is only 4.5 mm anyway, so it's unlikely you could correct it even if you had to...

Yeah, you'd be talking one tooth probably, and that would still probably overshoot it.

I'll just reconnect the speedo cable as is then - speaking of, is that on the left side of the trans? I need to get the car up in the rear so I can pop under and do that, so I haven't had a chance to look yet.

[81DaytonaPaceCar]

Yeah, you'd be talking one tooth probably, and that would still probably overshoot it.

I'll just reconnect the speedo cable as is then - speaking of, is that on the left side of the trans? I need to get the car up in the rear so I can pop under and do that, so I haven't had a chance to look yet.

Dunno about a 4-speed for sure, but I believe so.

Finally got caught up on all your pics. Looks like a fun little project. Let me throw this out there as food for thought:

1. Saw you were planning on taking the smog components off. I cannot emphasize this enough, but I'll only shout it out once.....ahem.....DO NOT UNDER ANY CIRCUMSTANCES THROW ANY OF IT AWAY. Emissions were evolving rapidly in the early 80s, and I know this is true for Pontiac (can only assume for Chevy), that 1980, 1981, and 1982 had unique part numbers/applications for the smog components. And I can virtually guarantee that a Cali setup is going to be unique for a 305/4-speed car. This stuff in used condition can go for a bunch of money, right down to the used and beat up catalytic converter. Ron has been trying to find the smog components for his 80 Indy Pace Car...for...years...

2. Back to tires quickly...tires are like shoes. Every manufacturer makes 'em just a little bit different. I've got 255 Bridgestone Pontenzas, and Bridgestone (used to) run a bit wider than the actual size (something like 257 or 258). BFGs (great tire) used to run a bit smaller than 255. So I don't think you running a 255 will be a big deal.

3. Back to emissions...does your car have a computer? I will guess that it does, and may actually have two. It will probably be underneath the center console. I had read that Joel pulled his out of his truck, and I never paid any mind to it at the time, but again.....ahem.....DO NOT THROW IT OUT. No you don't really need it, and yes, it can be bypassed, but these things can be rebuilt and can go for quite a bit of money.

4. The cap/rotor replacement issue. Your distributor may be unique to that vehicle, and it may contain a chip inside of it that talks to the (probable) spark computer. Again, unsure of Chevy, but the 80 and 81 turbo Pontiacs are unique for the year and unique for the computer. If the chip in the distributor goes bad, or the computer goes bad, the car won't run until they're replaced, or you just bypass the entire foolishness completely. Some 10 years ago, my distributor chip went bad, the shop that had the car discovered that there were no replacements for the '81 turbo chip anywhere. Fortunately, I had a spare '81 distributor sitting around, and that just turned into a $20 labor fix. Which is a nice segway TO...

5. Start hording parts. A lot of things are going to be '81 only parts for you. Do not just assume that a '79 or '80 will work, especially on electrical.

6. Now I've seen that you may want to do an engine/trans swap. You have a last-of-the-generation 4-speed car. Really not that many of them left around. Traditionally, a manual trans is roughly a 25% bump in value for that era of car. Add in the factory Air Induction, and it's a Cali car, that's going to be a pretty rare piece. Just throwing that out there...

Good luck with the new toy!

[9T8W66]

Kyle my 79 had 255/60's on it when I bought it. These were on the 15x7 snowflakes. They fit but had a pretty big bulge to them. I would recommend a 245/60 instead.

[81DaytonaPaceCar]

Idle thought that would be interesting (well, for me anyway...lol), is go find a early 70s 400 small block. Getting harder to find as they've found their way into a lot of race cars, but they made tons of them. It bolts right in, bolts up to your trans, and if you kept the Air Induction (almost a "must do"), you could easily double your horsepower and nobody would be the wiser for what was lurking under there. An easy to do and affordable power solution.

[MP81]

Dunno about a 4-speed for sure, but I believe so.

Finally got caught up on all your pics. Looks like a fun little project. Let me throw this out there as food for thought:

1. Saw you were planning on taking the smog components off. I cannot emphasize this enough, but I'll only shout it out once.....ahem.....DO NOT UNDER ANY CIRCUMSTANCES THROW ANY OF IT AWAY. Emissions were evolving rapidly in the early 80s, and I know this is true for Pontiac (can only assume for Chevy), that 1980, 1981, and 1982 had unique part numbers/applications for the smog components. And I can virtually guarantee that a Cali setup is going to be unique for a 305/4-speed car. This stuff in used condition can go for a bunch of money, right down to the used and beat up catalytic converter. Ron has been trying to find the smog components for his 80 Indy Pace Car...for...years...

2. Back to tires quickly...tires are like shoes. Every manufacturer makes 'em just a little bit different. I've got 255 Bridgestone Pontenzas, and Bridgestone (used to) run a bit wider than the actual size (something like 257 or 258). BFGs (great tire) used to run a bit smaller than 255. So I don't think you running a 255 will be a big deal.

3. Back to emissions...does your car have a computer? I will guess that it does, and may actually have two. It will probably be underneath the center console. I had read that Joel pulled his out of his truck, and I never paid any mind to it at the time, but again.....ahem.....DO NOT THROW IT OUT. No you don't really need it, and yes, it can be bypassed, but these things can be rebuilt and can go for quite a bit of money.

4. The cap/rotor replacement issue. Your distributor may be unique to that vehicle, and it may contain a chip inside of it that talks to the (probable) spark computer. Again, unsure of Chevy, but the 80 and 81 turbo Pontiacs are unique for the year and unique for the computer. If the chip in the distributor goes bad, or the computer goes bad, the car won't run until they're replaced, or you just bypass the entire foolishness completely. Some 10 years ago, my distributor chip went bad, the shop that had the car discovered that there were no replacements for the '81 turbo chip anywhere. Fortunately, I had a spare '81 distributor sitting around, and that just turned into a $20 labor fix. Which is a nice segway TO...

5. Start hording parts. A lot of things are going to be '81 only parts for you. Do not just assume that a '79 or '80 will work, especially on electrical.

6. Now I've seen that you may want to do an engine/trans swap. You have a last-of-the-generation 4-speed car. Really not that many of them left around. Traditionally, a manual trans is roughly a 25% bump in value for that era of car. Add in the factory Air Induction, and it's a Cali car, that's going to be a pretty rare piece. Just throwing that out there...

Good luck with the new toy!

1. Yep, that was the plan. I have a bad habit of just never throwing anything that might have any kind of value above $0 away. I'll just need to make space on the big shelving unit in my basement already full of car shit.

2. Makes sense - I forgot that some tires do run a little smaller.

3. Yes, '81 was the first year for CCC, so I should have an ECU somewhere. Current plan is to keep that intact with the 305.

4. I have the old one I just replaced, as well as a second new spare that came in the box - so two spares in total. I'm not sure if they're unique to '81 or not, but the distributor is fully electric as far as advance is concerned.

5. Yeah, I'm usually pretty picky - I'll do a bunch of research if I'm buying something for a different year - which is generally why it takes me forever to order anything.

6. Yup, definitely not common - the air induction is a cool little addition. Obviously doesn't do much - but it's definitely something you'd expect in that period of vehicles.

Kyle my 79 had 255/60's on it when I bought it. These were on the 15x7 snowflakes. They fit but had a pretty big bulge to them. I would recommend a 245/60 instead.

Good to know - I think I read something similar there, since a 7" rim is right on the low side of recommended wheel width.

Idle thought that would be interesting (well, for me anyway...lol), is go find a early 70s 400 small block. Getting harder to find as they've found their way into a lot of race cars, but they made tons of them. It bolts right in, bolts up to your trans, and if you kept the Air Induction (almost a "must do"), you could easily double your horsepower and nobody would be the wiser for what was lurking under there. An easy to do and affordable power solution.

Not a bad idea. Just something about a modern engine/transmission in an old car calls to me. But we'll see...

[81DaytonaPaceCar]

6. Yup, definitely not common - the air induction is a cool little addition. Obviously doesn't do much - but it's definitely something you'd expect in that period of vehicles.

May do more than you think. This is one of those things that, while it doesn't necessarily give you free horsepower, it is critical to not rob you of horsepower. Too many underhood assemblies, especially from back in the day, are Warm Air Intakes, just sucking in the 200+ degree hot underhood air and recycling it back through the engine. This just costs horsepower, especially on hot summer days. That cool little Air Induction effectively eliminates that failure mode.

For grins and giggles, I eBay'd what a '81 Air Induction air cleaner assembly was going for. There were only 2 complete ones...one at $225 and one at $265. Just the solenoid that opens/shuts the hood was $45.

Fun times!

[MP81]

That would make sense - and all that clutch fan does is blow hot air everywhere, making it hotter. I may actually take it upon myself to replace that with an electric fan, and I'll never have to be worried in traffic - and it also won't be running all the time. I'm also slightly terrified of that giant razorblade spinning all the time.

I was happy to find the solenoid still worked.

[bri2203]

The factory 15x7 N90s (what is currently on there) for now (255/60 BFG T/A is good for 7-9" wheels).

255/60R15 IMO look terrible on a 7" wheel. Even 245/60R15 look bad on a 7" wheel.
I am a few pages behind on your progress so hopefully my comment is not too late.

I spent the extra money on the BFGs on my 81 corvette. You should by the wheels and tires.......and the rest of the car.

[MP81]

255/60R15 IMO look terrible on a 7" wheel. Even 245/60R15 look bad on a 7" wheel.
I am a few pages behind on your progress so hopefully my comment is not too late.

I spent the extra money on the BFGs on my 81 corvette. You should by the wheels and tires.......and the rest of the car.

Nope, not too late - just been looking into tires more now, since I'm probably a week or two away from having a title...maybe.

And I'm not sure I need another 1981 project.

[JoeliusZ28]

Good info Jeff. For the record i didnt take the electric spark control out of my truck i just bypassed it. It did fail for some unknown reason i can put it back into service if i buy another module. Seems to run just fine without it though, as advance is primarily controlled by springs and vacuum, the ESC was just a fail safe for spark knock. If kyles is full electric im guessing he doesnt have that option.

Also i havent seen pictures of these tire sizes, but i tend to agree with Brian i wouldnt want to increase tire height (and thus sidewall) when you already had a large sidewall to begin with.

[MP81]

Good info Jeff. For the record i didnt take the electric spark control out of my truck i just bypassed it. It did fail for some unknown reason i can put it back into service if i buy another module. Seems to run just fine without it though, as advance is primarily controlled by springs and vacuum, the ESC was just a fail safe for spark knock. If kyles is full electric im guessing he doesnt have that option.

Also i havent seen pictures of these tire sizes, but i tend to agree with Brian i wouldnt want to increase tire height (and thus sidewall) when you already had a large sidewall to begin with.

I think the issue is more of the tire bulge you'll get putting a 255/60 on a 7" rim. It fits and it works - but the tire is happier on a wider wheel.

A 255/60 is actually 0.4" shorter than a 225/70.

And correct - no option to bypass, other than disconnecting the ability for it to electronically advance timing. If my last time running the car was any indicator, I don't think it is artificially advancing timing at idle, bringing up RPM, but may just literally be something sticking in the carb. It was idling at about 1500-2k with the distributor unplugged, and you could see it trying to drop past 1500, but it seemed like something was holding it back. A few revs later, she dropped right to 750 - and idle speed didn't seem to jump up when I reconnected the distributor.