235/60/15
Thread Starter
Pro
Joined: Oct 2013
Posts: 557
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From: El Sobrante CA
235/60/15
I know that 'GR-70' was the original tire spec for '76 (and other years.). Dunlop 235/70s were on my '76 before I put the car on stands for garage work. Since the tires looked like they'd been around since the Korean War, I ran a sidewall crack test. Three tires failed miserably.
Long story short, I got a deal on a set of new Cooper 235/60s. I'm wondering what the upsides and downsides of my choice are. Not planning to do an engine beef up from the stock 350/AT; just want decent handling a cruisabilty. I expect my speedo might be a little off. But, other than that, I'm interested in what your experiences have been with this slightly shorter tire.
Thanks.
Dan G>
Long story short, I got a deal on a set of new Cooper 235/60s. I'm wondering what the upsides and downsides of my choice are. Not planning to do an engine beef up from the stock 350/AT; just want decent handling a cruisabilty. I expect my speedo might be a little off. But, other than that, I'm interested in what your experiences have been with this slightly shorter tire.
Thanks.
Dan G>
Last edited by Capkunu; Nov 15, 2013 at 11:43 AM.
Thread Starter
Pro
Joined: Oct 2013
Posts: 557
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From: El Sobrante CA
Thanks for the reply.
Dan G>
Race Director
Joined: May 2006
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Naturally all of the above are better. The 235/60 is about 1" smaller in diameter. At 60 mph you will be doing approx. 58 mph. So is it worth it to you to correct this and then there is the issue of is there a gear that will compensate for such a minor difference. If you install them check your speed with a GPS to get an actual variation from the reading on the speedometer.
Thread Starter
Pro
Joined: Oct 2013
Posts: 557
Likes: 3
From: El Sobrante CA
Naturally all of the above are better. The 235/60 is about 1" smaller in diameter. At 60 mph you will be doing approx. 58 mph. So is it worth it to you to correct this and then there is the issue of is there a gear that will compensate for such a minor difference. If you install them check your speed with a GPS to get an actual variation from the reading on the speedometer.
Thanks for the reply!
Dan G>
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
G70-15's are equivalent to 225 width radial tires. So, going to 235's will get you a little more tire width. If you go to 245's, the overall diameter of the 60 series tire may be about the same as the G70's, so that may not require any change to the speedo gearing.
I have 235R60-15's on my '71 and they are just right, IMO. They fill the wheelwell, but don't stick out; they are the right diameter (compared to original F or 215 width tires); and they handle very well when aired up to 32 psi.
I have 235R60-15's on my '71 and they are just right, IMO. They fill the wheelwell, but don't stick out; they are the right diameter (compared to original F or 215 width tires); and they handle very well when aired up to 32 psi.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
I know that 'GR-70' was the original tire spec for '76 (and other years.). Dunlop 235/70s were on my '76 before I put the car on stands for garage work. Since the tires looked like they'd been around since the Korean War, I ran a sidewall crack test. Three tires failed miserably.
Long story short, I got a deal on a set of new Cooper 235/60s. I'm wondering what the upsides and downsides of my choice are. Not planning to do an engine beef up from the stock 350/AT; just want decent handling a cruisabilty. I expect my speedo might be a little off. But, other than that, I'm interested in what your experiences have been with this slightly shorter tire.
Thanks.
Dan G>
Long story short, I got a deal on a set of new Cooper 235/60s. I'm wondering what the upsides and downsides of my choice are. Not planning to do an engine beef up from the stock 350/AT; just want decent handling a cruisabilty. I expect my speedo might be a little off. But, other than that, I'm interested in what your experiences have been with this slightly shorter tire.
Thanks.
Dan G>
My '80 L48 came with the P255-60R15's but I think the P225-60R15 was standard beginning with '78 once GM started running radial tires.
With Goodyear discontinuing the 60R15 and 70R15 profiles with RWL's, Cooper, BFG and the few others are all that remain... unless you want to pay Coker $350 per tire. I think Cooper also manufactures Mickey Thompson but I may be mistaken on that.
Thread Starter
Pro
Joined: Oct 2013
Posts: 557
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From: El Sobrante CA
Cooper makes good replacement tires. I picked up the Mastercraft Avenger G/T (also by Cooper) for about $125 each (2) in P255-60R15.
My '80 L48 came with the P255-60R15's but I think the P225-60R15 was standard beginning with '78 once GM started running radial tires.
With Goodyear discontinuing the 60R15 and 70R15 profiles with RWL's, Cooper, BFG and the few others are all that remain... unless you want to pay Coker $350 per tire.
My '80 L48 came with the P255-60R15's but I think the P225-60R15 was standard beginning with '78 once GM started running radial tires.
With Goodyear discontinuing the 60R15 and 70R15 profiles with RWL's, Cooper, BFG and the few others are all that remain... unless you want to pay Coker $350 per tire.
I've had Coopers on other cars I've owned; can't recall any complaints with those. Price was definitely a concern; got this set mounted at Sears Discount for $410 out the door.Dan G>
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Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
If you look on tire sites and other sources for the sizes that fit the later C3s, its 225/70/15 or 255/60/15.
Back in the early 2000s when I was selling tires, someone brought in a C3 with 225/70/15 tires. I was trying to convince him to go with the wider 255/60/15 but he decided to stick with the 225/70/15.
Once I saw them installed on the 8" wheel, I thought he made the right choice. They fit the car really well.
I have 225/60/HR15 tires on my C3 and I'd like to change them over to 255/60R15 with outside white letters.
225/70/15 = 27.4" OD
255/60/15 = 27.1" OD
Source
Back in the early 2000s when I was selling tires, someone brought in a C3 with 225/70/15 tires. I was trying to convince him to go with the wider 255/60/15 but he decided to stick with the 225/70/15.
Once I saw them installed on the 8" wheel, I thought he made the right choice. They fit the car really well.
I have 225/60/HR15 tires on my C3 and I'd like to change them over to 255/60R15 with outside white letters.
225/70/15 = 27.4" OD
255/60/15 = 27.1" OD
Source
