Tim Posted July 5, 2022 Share Posted July 5, 2022 My tires are old (discovered splits between the treads) - dated 2013. I'm looking at the difference between 70R and 75R. I don't think there's an issue with the sidewall height, but I'd thought I'd check. Link to comment Share on other sites More sharing options...
old yeller Posted July 5, 2022 Share Posted July 5, 2022 The 70 is wider than the 75 (width). The 215, 225 etc is the height (diameter) of the tire. Link to comment Share on other sites More sharing options...
Tim Posted July 5, 2022 Author Share Posted July 5, 2022 The question I'll need to answer is how much difference would 75 make on my C3 vs 70 - fitment with the taller sidewall. The tire width will be 225. Link to comment Share on other sites More sharing options...
Chameleon Posted July 5, 2022 Share Posted July 5, 2022 30 minutes ago, Tim said: The question I'll need to answer is how much difference would 75 make on my C3 vs 70 - fitment with the taller sidewall. The tire width will be 225. By my calculations (subject to human error of course) the difference in tire diameter/height between 70 and 75 on a 225 tire, the 75 will be slightly less than an inch taller tire. Will that fit in your wheel wells without rubbing in a lock-to-lock turn? Link to comment Share on other sites More sharing options...
Tim Posted July 5, 2022 Author Share Posted July 5, 2022 GRABBING THE TAPE MEASURE!!!! THANKS!! 1 Link to comment Share on other sites More sharing options...
Extender32 Posted July 5, 2022 Share Posted July 5, 2022 On Julies 78, she has 255/60/15. Link to comment Share on other sites More sharing options...
Chameleon Posted July 5, 2022 Share Posted July 5, 2022 1 hour ago, Extender32 said: On Julies 78, she has 255/60/15. That is a wider, and much shorter tire than a 225/70/17 Link to comment Share on other sites More sharing options...
Buccaneer Posted July 6, 2022 Share Posted July 6, 2022 A 255x60x15 tire which is what mine are as well are a 27" tire. To see what a different tire will be...Go here and put in the tire size you want and it will give you the spec and alternate size tires. TIRE CAL 1 Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 25 minutes ago, Buccaneer said: A 255x60x15 tire which is what mine are as well are a 27" tire. To see what a different tire will be...Go here and put in the tire size you want and it will give you the spec and alternate size tires. TIRE CAL That is a good site to use!! Thank you!!! 255/70R15=27.4x8.9R15 These will be the fronts. Do you think either of these would work for the rear? Leaning toward the 235/70R15 235/75R15 = 28.9X9.3R15 28.9 more than an inch taller and not much wider than the 255/70 235/70R15 = 28.0x9.3R15 Not much taller or wider Shouldn't be an issue with a larger set on the back? Thanks for the help and for sharing your opinions.!! Tim Link to comment Share on other sites More sharing options...
JohnU Posted July 6, 2022 Share Posted July 6, 2022 225/70/15 on all corners so you can rotate them. Forget the 75's, your putting them on the cornering machine! Are you using the factory rally wheels or the optional aluminum wheels or aftermarket wheels with unknown offset? You could run the 255/60/15's Extender32 and I use on our later C3's.... but watch the front edge of the front fenders for interference. The factory cut them back a touch for the '78 pace car and Anniversary to run the 255's. Some run the 245/60/15's on the early C3's to be safe. Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 12 minutes ago, JohnU said: 225/70/15 on all corners so you can rotate them. Forget the 75's, your putting them on the cornering machine! Are you using the factory rally wheels or the optional aluminum wheels or aftermarket wheels with unknown offset? You could run the 255/60/15's Extender32 and I use on our later C3's.... but watch the front edge of the front fenders for interference. The factory cut them back a touch for the '78 pace car and Anniversary to run the 255's. Some run the 245/60/15's on the early C3's to be safe. Thanks John. Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 7 minutes ago, Tim said: Thanks John. wheels are 15"x8" factory Steel wheels 1 Link to comment Share on other sites More sharing options...
HOXXOH Posted July 6, 2022 Share Posted July 6, 2022 Go here to find your actual speed at any RPM for whatever size tire you decide to use. Then you can compare that with your speedometer to find the difference. http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php 1 Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 2 hours ago, HOXXOH said: Go here to find your actual speed at any RPM for whatever size tire you decide to use. Then you can compare that with your speedometer to find the difference. http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php I will do that....LOL...as soon as get the speed-o-meter to work oh and the tach...yup...it's a project!!! Thanks!! Tim Link to comment Share on other sites More sharing options...
JohnU Posted July 6, 2022 Share Posted July 6, 2022 A can of argent silver spray paint and white letter tires and you'll look like this. Link to comment Share on other sites More sharing options...
JohnU Posted July 6, 2022 Share Posted July 6, 2022 2 hours ago, Tim said: Tim, Does the top of the center cap protrude past the trim ring? Those might be the earlier 15x7 rim vs the 15x8 in the previous picture. Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 I like that. Thanks. going to steel pic for later ref!!! Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 5 minutes ago, JohnU said: Tim, Does the top of the center cap protrude past the trim ring? Those might be the earlier 15x7 rim vs the 15x8 in the previous picture. There is a little space where my finger is Link to comment Share on other sites More sharing options...
Tim Posted July 6, 2022 Author Share Posted July 6, 2022 Last question 235s on the back? 225 on front. Thanks Tim Link to comment Share on other sites More sharing options...
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