Frequently Asked Questions

Q: Billing History Card Decode for Fiberglass Belted Tires

I just received my billing history from PHS. The tire protion reads as follows:

F70x14 RL FG $57.93 TMT $41.80 $2.93

What did these codes represent?

A: ….This is the breakdown for the type of Tires that were originally installed on your Firebird. (F70x14 Redlines, Fiberglass-Belted). The “TMT” is the Sales Code for that particular tire. The amounts listed are Tire Cost and Final Destination and Handling Charges.

The Fiberglass Belted Tires were NOT a mid-year upgrade in 1969; that happened for the 1968 model year.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: 255’s or 235’s on 15×7 Ralley IIs

Does anyone know if 255 70 R15’s or 255 90 R15’s will rub on 15x 7 Ralley II’s if I put them under my 1968 Firebird 400 car? I know I’ve heard much about this in the past.But just cant recall.

A: I’ll assume that the above “255 90 R15” is really 255 60 R15. A 90 series tire would be very tall and skinny indeed.

What will fit will depend partially on how much, if any, your car sags in the rear, or has been lowered in any way. So a simple answer is difficult to offer that would be accurate in any way.

Here is how the tires stack up in diameter:

As you can see, the 70 series tires are noticably taller than the 60 series tires, and some of these sizes are more than 3.5″ taller than the stock tire. You need to check your present clearance to see if you can fit tires these sizes as your car sits now. Air shocks will of course get you more clearance, but they have their own problems and I would not reccommend their use.

Up front, many owners run 225/60 or 70-15s, and I run 235/60-15 without problems. others report rubbing with some of these sizes. I get a little rubbing on steep or off-camber driveways. I think that a 255/70 or 60 in front is too tall and would definately rub unless your car sat very high. At least one member reports running 245/50-15 up front, and he can tell you about what problems if any he’s encountered. I find that this is too wide for my car with my present offset wheels. That’s a 7 inch Ralley II.

In back, members have reported running 255/60s without much trouble. I think that a 7 inch wheel my be too narrow for this tire and will not allow the tread to fully meet the road surface. Excessive wear in the middle will result, and you will not get the full effect of this width tire. An 8 inch wheel will be much better. An offset of 4.5 inches should allow you get that tire inside the wheel well, though at 27 inches tall, you need to check for adaquate clearance.

A: Been several posts in the past on this Biggest size on an unaltered 67-9 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes,I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Largest Size Wheels Can I Put on My 1968

What is the largest size wheels I can put on the rear and front without any modifications to a pretty much stock-like drivetrain set-up? I have traction bars on the rear, but that’s about it. Right now I have 14×6″ Rally II’s on the front, and 14×7 Rally II’s on the rear. I wanted to get some 15×7 or even 8″ wheels to put on the rear and was wondering if this would fit without any modifications being necessary. Jeg’s is selling Rally II replica wheels for only $92ea for the 15×8’s!

A: 15×8 will not fit inside the stock wheelwells. The front and rear will handle up to 235-60×15 without a problem. The rear could go up to 255 if you roll the lip of the quarter/wheelhouse. Remember, rim offset is critical. If you plan on using after market wheels a good rule of thumb is to lay a straight edge vertically on the front of the drum then measure the distance from the edge to the fron and back of the wheelhouse. Give yourself 1″ (max clearance) to 1/2″ (min clearance) on each side to allow for tire sidewall buldge.

A: I put 15 x 7 with 235 60 15 on my 1967 and it looks great. It had 14 x 6 on it but now the fender wells are full and looks great.

A: I have seen a 1968 with 15×8 wheels and 275/50/15 tires on the rear. They loked great and did not rub. The wheels did seem a bit narow for those tires (I would go with 9.5 to 10 inch wide, as 275 tires are almost 11 inches wide) but the owner was only concerned with straight line performance only. I don’t have information on backspacing, but I see Camaros of the same year running around like that all the time. I would assume it is common knowlege at the wheel store. 235/60/15 is as wide as I would go in the front but they would have an outside diameter that is slightly larger that your rears (235/60/15= 26.1in. outside diameter, 275/50/15= 25.83in.). I suggest 225/60/15 in the front for this reason (25.63in. outside diameter). Tires of smaller or significantly larger diameter in the rear can have adverse effects on handeling. It’s fine at the strip, but a chore on the street.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Maximum Wheel and Tire Sizes

What is the largest size tires I can put on my Firebird?

A: The March 2000 issue of Car Craft has an article that deals with maximum wheel and tire sizes for various cars. It has a section on the 1967, 1968, and 1969 Camaro and Firebird and below is the text of that portion of the article.

A: Been several posts in the past on this Biggest size on an unaltered 1967, 1968, 1969 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes, I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Original Tires

Can someone tell me what tires were original on a 1968 400 Firebird?

A: Several types of tires (Firestone) were used on the 1968 Firebird.

Standard on the Base Firebird was the E70x14 B/W Wide Oval.
Standard on the Sprint, 350, 350 & 350 HO was the F70x14 B/W.
Only the 400 Model received the F70x14 Redline Wide Oval.

Optional were:

E70x14 Redlines
E70x14 Whitewall
I95Rx14 Whitewall Radial (rayon)
F70x14 Redline, Whitewall & Blackwall

The type of tire was noted on the Fisher Body Broadcast Copy and on the PMD Billing History Card

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Reproduction Goodyear Polyglass Tires

I’m about to spend a whole lot of money for new tires to put on my 1967. I’m planning on coughing up the big $$$ for the period correct Goodyear Polyglass tires that classic industries resells. The problem I have is; which size to go with, the F70-14 or the E70-14? The car originally came with E70-14s, but I seem to recall that back in high school, (a very long tiome ago), I had a set of F70-14s mounted on 14 x 7 Rally IIs, and I don’t remember having any clearance problems then.

Currently, my car has Goodyear Eagle VRs, mounted on 15 x 7 Rally II rims. The tires are size P225/60VR15. I don’t have any clearance problems right now. As far as I know, the car is riding on a stock suspension, except that the coil spring pads in the front have been removed by the prevoius owner, so the front end may be sitting about 1/2″ lower than stock.

A: The 225R60-15 is a very close diameter to the G60-15 and F70-15 size. My 1967 has 255R60-15 on the rear and 205R60-15 on the front. I’m toying with the idea of going to 225R60-16 all around.

A: Make sure to get 15 inch tires to go on the 15 inch rims or\ replace the rims with correct 14 x 6 rims.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Tires for 14×7 Rally II Rims

I have set of 14*7″ rallye II rims that i’m going to put some rubber on. Does anyone know what size tire i can get on these and fit them comfortably inside a 1967 wheel well?

A: I dont know what offset your wheels have so use the following: all around size is 225-60×14 to be safe I have used 235 in front (rear is no problem) but its close. Rear can go with a 255 or 265 but depends on offset. I personally have grown out of the mismatched front to rear for a street driven car. All of these sizes can be put on a 7in wide rim

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Vibration

I finally got my car out this summer and at about 50mph the car began to “resonate”. I could feel a vibration through the steering wheel and the pedals. Once I hit about 65mph, it went away and the car cruised great again. The vibration is there regardless of what gear I’m in and it doesn’t matter if I’m accelerating or braking. I drove the car around for hours reproducing the vibration and trying to figure out what it is and to see if whatever it is would let go on me. It did not get any worse or any better.

Based on my “testing” I don’t think it’s engine or transmission related. I think it’s probably something in the rear (driveshaft and back). I’m going to pull the driveshaft this weekend and have it balanced and get new u-joints installed as well. If that doesn’t work I’ll try getting the tires balanced and rotated. If that doesn’t work………..? Does anyone have Currie’s web address? 🙁

Any ideas or experiences would be greatly appreciated.

A: check u joints first. i had a similar problem……..turnd out to be a loose u joint.

A: Check the tire balance. If you feel it more through the wheel it’s in the front. If it’s the whole car in general it’s the rear. Maybe a tire went out of round from sitting. At any rate check the easy stuff first!

A: As I was reading your description of your problem I was thinking U-joints. So, glad to see we are on the same page. The other obvious questions are:

• The rotors. Is there any “pulsation” when you break at a slow speed?

• Have you looked at the wheel bearing, front and back?

• This may sound strange but check your shocks. If one has collapsed it could set up a resonance.

• Could b flat spots on the tires.

A: And now the answer for people who, like me foolishly let someone else put on their wheels. About oh say 20 years ago, I took my car out of winter storage. For the winter, I removed the wheels and tires and put it up on blocks. In spring, a friend helped me mount the wheels. I took it out for a spin and had the exact same problem as you. Turned out my friend didn’t torque the lug nuts on one tire tight enough. I was darn embarassed when the local garage found them all to be loose. But hey… life goes on. I married my friend anyway.

A: I think its has to do with the tires but here is some extra stuff to look at. Two hard to track down vibrations problems I have had are the following

Bad motor and trans mounts (all 3 bad at the same time) and Bad rubber rear leaf spring cushion. This caused the rear end to move slightly out of line and float. It felt like the whole car was going to self destruct. (it was very inconstant) It was by dumb luck that I discovered the problem. Also if you body mounts are bad the car is less tolerant of bad tires.

A: It appears to be a simple wheel/tire balance problem. If in doubt about whether the tires will balance properly, look for a tire dealer with the newest balance technology, the load force variance type machines. They apply a road load to the surface of the tire while spinning the wheel/tire assembly, and can determine if there’s a problem in the tire (such as a belt shift or other imperfections), and even tells the tech if the tire needs to be indexed differently on the rim.

I worked at a Buick GMC dealer that had this machine, it was a Hunter 9000 I think, and we could condemn defective tires all day long on this thing. The down side is it’s labor intensive, and requires a tire technician who can actually think. If you need to index all 4 tires, that means attempting the balance, determining the index position, moving the assembly to the tire changing machine and breaking it down, moving the tire to the new index and re-inflating it. Figure about 2 hours shop labor for all four.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: 255’s or 235’s on 15×7 Ralley IIs

Does anyone know if 255 70 R15’s or 255 90 R15’s will rub on 15x 7 Ralley II’s if I put them under my 1968 Firebird 400 car? I know I’ve heard much about this in the past.But just cant recall.

A: I’ll assume that the above “255 90 R15” is really 255 60 R15. A 90 series tire would be very tall and skinny indeed.

What will fit will depend partially on how much, if any, your car sags in the rear, or has been lowered in any way. So a simple answer is difficult to offer that would be accurate in any way.

Here is how the tires stack up in diameter:

As you can see, the 70 series tires are noticably taller than the 60 series tires, and some of these sizes are more than 3.5″ taller than the stock tire. You need to check your present clearance to see if you can fit tires these sizes as your car sits now. Air shocks will of course get you more clearance, but they have their own problems and I would not reccommend their use.

Up front, many owners run 225/60 or 70-15s, and I run 235/60-15 without problems. others report rubbing with some of these sizes. I get a little rubbing on steep or off-camber driveways. I think that a 255/70 or 60 in front is too tall and would definately rub unless your car sat very high. At least one member reports running 245/50-15 up front, and he can tell you about what problems if any he’s encountered. I find that this is too wide for my car with my present offset wheels. That’s a 7 inch Ralley II.

In back, members have reported running 255/60s without much trouble. I think that a 7 inch wheel my be too narrow for this tire and will not allow the tread to fully meet the road surface. Excessive wear in the middle will result, and you will not get the full effect of this width tire. An 8 inch wheel will be much better. An offset of 4.5 inches should allow you get that tire inside the wheel well, though at 27 inches tall, you need to check for adaquate clearance.

A: Been several posts in the past on this Biggest size on an unaltered 67-9 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes,I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Billing History Card Decode for Fiberglass Belted Tires

I just received my billing history from PHS. The tire protion reads as follows:

F70x14 RL FG $57.93 TMT $41.80 $2.93

What did these codes represent?

A: ….This is the breakdown for the type of Tires that were originally installed on your Firebird. (F70x14 Redlines, Fiberglass-Belted). The “TMT” is the Sales Code for that particular tire. The amounts listed are Tire Cost and Final Destination and Handling Charges.

The Fiberglass Belted Tires were NOT a mid-year upgrade in 1969; that happened for the 1968 model year.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Largest Size Wheels Can I Put on My 1968

What is the largest size wheels I can put on the rear and front without any modifications to a pretty much stock-like drivetrain set-up? I have traction bars on the rear, but that’s about it. Right now I have 14×6″ Rally II’s on the front, and 14×7 Rally II’s on the rear. I wanted to get some 15×7 or even 8″ wheels to put on the rear and was wondering if this would fit without any modifications being necessary. Jeg’s is selling Rally II replica wheels for only $92ea for the 15×8’s!

A: 15×8 will not fit inside the stock wheelwells. The front and rear will handle up to 235-60×15 without a problem. The rear could go up to 255 if you roll the lip of the quarter/wheelhouse. Remember, rim offset is critical. If you plan on using after market wheels a good rule of thumb is to lay a straight edge vertically on the front of the drum then measure the distance from the edge to the fron and back of the wheelhouse. Give yourself 1″ (max clearance) to 1/2″ (min clearance) on each side to allow for tire sidewall buldge.

A: I put 15 x 7 with 235 60 15 on my 1967 and it looks great. It had 14 x 6 on it but now the fender wells are full and looks great.

A: I have seen a 1968 with 15×8 wheels and 275/50/15 tires on the rear. They loked great and did not rub. The wheels did seem a bit narow for those tires (I would go with 9.5 to 10 inch wide, as 275 tires are almost 11 inches wide) but the owner was only concerned with straight line performance only. I don’t have information on backspacing, but I see Camaros of the same year running around like that all the time. I would assume it is common knowlege at the wheel store. 235/60/15 is as wide as I would go in the front but they would have an outside diameter that is slightly larger that your rears (235/60/15= 26.1in. outside diameter, 275/50/15= 25.83in.). I suggest 225/60/15 in the front for this reason (25.63in. outside diameter). Tires of smaller or significantly larger diameter in the rear can have adverse effects on handeling. It’s fine at the strip, but a chore on the street.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Maximum Wheel and Tire Sizes

What is the largest size tires I can put on my Firebird?

A: The March 2000 issue of Car Craft has an article that deals with maximum wheel and tire sizes for various cars. It has a section on the 1967, 1968, and 1969 Camaro and Firebird and below is the text of that portion of the article.

A: Been several posts in the past on this Biggest size on an unaltered 1967, 1968, 1969 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes, I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Original Tires

Can someone tell me what tires were original on a 1968 400 Firebird?

A: Several types of tires (Firestone) were used on the 1968 Firebird.

Standard on the Base Firebird was the E70x14 B/W Wide Oval.
Standard on the Sprint, 350, 350 & 350 HO was the F70x14 B/W.
Only the 400 Model received the F70x14 Redline Wide Oval.

Optional were:

E70x14 Redlines
E70x14 Whitewall
I95Rx14 Whitewall Radial (rayon)
F70x14 Redline, Whitewall & Blackwall

The type of tire was noted on the Fisher Body Broadcast Copy and on the PMD Billing History Card

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Reproduction Goodyear Polyglass Tires

I’m about to spend a whole lot of money for new tires to put on my 1967. I’m planning on coughing up the big $$$ for the period correct Goodyear Polyglass tires that classic industries resells. The problem I have is; which size to go with, the F70-14 or the E70-14? The car originally came with E70-14s, but I seem to recall that back in high school, (a very long tiome ago), I had a set of F70-14s mounted on 14 x 7 Rally IIs, and I don’t remember having any clearance problems then.

Currently, my car has Goodyear Eagle VRs, mounted on 15 x 7 Rally II rims. The tires are size P225/60VR15. I don’t have any clearance problems right now. As far as I know, the car is riding on a stock suspension, except that the coil spring pads in the front have been removed by the prevoius owner, so the front end may be sitting about 1/2″ lower than stock.

A: The 225R60-15 is a very close diameter to the G60-15 and F70-15 size. My 1967 has 255R60-15 on the rear and 205R60-15 on the front. I’m toying with the idea of going to 225R60-16 all around.

A: Make sure to get 15 inch tires to go on the 15 inch rims or\ replace the rims with correct 14 x 6 rims.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Tires for 14×7 Rally II Rims

I have set of 14*7″ rallye II rims that i’m going to put some rubber on. Does anyone know what size tire i can get on these and fit them comfortably inside a 1967 wheel well?

A: I dont know what offset your wheels have so use the following: all around size is 225-60×14 to be safe I have used 235 in front (rear is no problem) but its close. Rear can go with a 255 or 265 but depends on offset. I personally have grown out of the mismatched front to rear for a street driven car. All of these sizes can be put on a 7in wide rim

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.

Q: Vibration

I finally got my car out this summer and at about 50mph the car began to “resonate”. I could feel a vibration through the steering wheel and the pedals. Once I hit about 65mph, it went away and the car cruised great again. The vibration is there regardless of what gear I’m in and it doesn’t matter if I’m accelerating or braking. I drove the car around for hours reproducing the vibration and trying to figure out what it is and to see if whatever it is would let go on me. It did not get any worse or any better.

Based on my “testing” I don’t think it’s engine or transmission related. I think it’s probably something in the rear (driveshaft and back). I’m going to pull the driveshaft this weekend and have it balanced and get new u-joints installed as well. If that doesn’t work I’ll try getting the tires balanced and rotated. If that doesn’t work………..? Does anyone have Currie’s web address? 🙁

Any ideas or experiences would be greatly appreciated.

A: check u joints first. i had a similar problem……..turnd out to be a loose u joint.

A: Check the tire balance. If you feel it more through the wheel it’s in the front. If it’s the whole car in general it’s the rear. Maybe a tire went out of round from sitting. At any rate check the easy stuff first!

A: As I was reading your description of your problem I was thinking U-joints. So, glad to see we are on the same page. The other obvious questions are:

• The rotors. Is there any “pulsation” when you break at a slow speed?

• Have you looked at the wheel bearing, front and back?

• This may sound strange but check your shocks. If one has collapsed it could set up a resonance.

• Could b flat spots on the tires.

A: And now the answer for people who, like me foolishly let someone else put on their wheels. About oh say 20 years ago, I took my car out of winter storage. For the winter, I removed the wheels and tires and put it up on blocks. In spring, a friend helped me mount the wheels. I took it out for a spin and had the exact same problem as you. Turned out my friend didn’t torque the lug nuts on one tire tight enough. I was darn embarassed when the local garage found them all to be loose. But hey… life goes on. I married my friend anyway.

A: I think its has to do with the tires but here is some extra stuff to look at. Two hard to track down vibrations problems I have had are the following

Bad motor and trans mounts (all 3 bad at the same time) and Bad rubber rear leaf spring cushion. This caused the rear end to move slightly out of line and float. It felt like the whole car was going to self destruct. (it was very inconstant) It was by dumb luck that I discovered the problem. Also if you body mounts are bad the car is less tolerant of bad tires.

A: It appears to be a simple wheel/tire balance problem. If in doubt about whether the tires will balance properly, look for a tire dealer with the newest balance technology, the load force variance type machines. They apply a road load to the surface of the tire while spinning the wheel/tire assembly, and can determine if there’s a problem in the tire (such as a belt shift or other imperfections), and even tells the tech if the tire needs to be indexed differently on the rim.

I worked at a Buick GMC dealer that had this machine, it was a Hunter 9000 I think, and we could condemn defective tires all day long on this thing. The down side is it’s labor intensive, and requires a tire technician who can actually think. If you need to index all 4 tires, that means attempting the balance, determining the index position, moving the assembly to the tire changing machine and breaking it down, moving the tire to the new index and re-inflating it. Figure about 2 hours shop labor for all four.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.