Hello all,
Looking at some new shoes for my 73. It currently has 235/60/15 BFG's on it and they look to small. A 225/70/15 is the replacement that is close to the original size. I'm looking at Coopers and the 225/70/15 for the fronts, but 235/70/15 for the rears. Anyone else have that type of set up? Can I get a side shot so I can see how it would look as far as size difference. I don't want the car to look like it's on air shocks. Just wanted a little more width in the back. Thanks

 

I don't know that visually you'd ever even notice the difference between a 225/70 and a 235/70. Going from the 225 to the 235 you're only adding about a 1/2" in diameter (27.4" to 27.9") and less than a half inch in tread width (6.8" to 7.2"). The 235/70's will be noticeably taller than your current (26.1" diameter) 235/60's, but the width will remain the same since they both have a 7.2" wide tread. If you didn't change your speedometer gear when you switched to the shorter 235/60's, going to the 235/70 should make it more accurate than it currently would be with the 60's on the car.

 

I know it will sit a lot higher with the 70's than the 60's, but it will be at factory height. The rear has 4:88's in it and the speedometer is verified reading correctly with the 60's on it. Once new tires are on and the rear gears swapped out then I will have redo the speedometer gear. Just wanted it to sit level and not riding high in the rear.

 

with everything stated by gbvette62. I have a 1979 with 235/70-15 BFG at all four corners. Speaking for myself, I love that tire size on the car.

As stated, you would hardly be able to distinguish the tire size difference looking at the profile of the car. The 235/70-15 is very slightly taller and slightly wider than the 225/70-15.

One issue you should be aware of is changing from a 26 to 28 inch tire will change your effective diff gear ratio. In your specific case, based on the info you provide above, you would effectively change your gear ratio from 4.88 to about a 4.60 ratio—if my math is right. In other words, with all other things being equal, the taller the drive tires are, the lower the effective gear ratio will be for any given car.

One other factor is that all 73-79 cars were fitted with 225/70-15 tires as the standard tire at the factory. When Chevrolet offered the 255/60-15 optional tire, they had to trim the front fenders of all 1978 & 1979 cars so fitted with the wider tire. My car originally had the wider optional tire and so still has that fender trimming treatment. Having said that, I don’t think the very slightly taller and wider 235/70-15 tire would be a problem compared to the 225/70-15, but I can’t guarantee it. The rear tires would pose absolutely no problem.

--------------------------
1979 L82 M21 FE7
Classic White / Doeskin

 

As the other members said....you won't notice the difference between a 225 and a 235 tire except for filling the wheel wells up nicely

IF you don't like the rear sitting high, I removed the thick top 12"(?) long "spacer" leaf...
and installed a thinner but stronger main leaf....
and installed bolts 1" longer which lowers the rear also.
My car sits 3.4" higher in the rear, but a full tank of gas and my 165 lbs. causes the car to sit nearly level front to rear.



I have 235-70 tires on all four wheels so I can rotate them every year so I can drive my car often)

 

I run a 245 60-15 on the front and a 255/60-15 on the rear. It fills the wheel wells nicely.

 

255/60/15 rear
245/6015 front
Cooper cobras just installed over the weekend, fills wheel wells nicely with no rubbing front fenders. Also went white letters out. Had bfg 255's all around but they rubbed on the front fenders.

Not really worried about rotating since just nice weather weekend warrior and has a good alignment.

 

Just put these on a month ago.
255/60/15 on all four corners.
I've run that same size on 4 69-72 C3's

 

I like meat.....255/60s all around for me too..

 

i went back with the original size a

nd white walls!!

 

255/60/15 rear; 245/60/15 front is perfect.