Have the opportunity to get some used bias-ply L78-15 tires off C'List. Question is, stock tires size for a '50 Buick Special is supposed to be 7.60 x 15. I believe the L78s end up being comparable to a 8.20 x 15. The '50 Roadmaster and Super used only a 8.0 x 15 when new. I know when the 7.60s are converted to radial size, they're a 225/75/15. The converted size of a L78 is 235/75/15. In the radial world, that equates to an almost negligible size difference. How would this difference in size affect a bias-ply? I've read soo many damn arguments about how bias-ply sizes can't truly convert to radials that I'm lost at this point. So back to basic question...is there a major difference in a 7.60 x 15 as compared to a 8.20 x 15 in a bias-ply tire? Quick turnaround on answer would be beneficial. Thanks!!
An inch taller, probably about an inch wider too. Will it fit? probably. Will they look a bit too large? maybe. http://www.dbtires.com/crossreference.html .
The L is close to a 9.00-15, much bigger than a 7.60 x 15. http://www.dbtires.com/crossreference.html
Squirrel and Bobs, now that info. puts it into a little better perspective. Like I said when I used the popular tacomaworld.com Tire Calculator, when comparing the radial measurements, it seemed like not much of a difference at all, but when truly comparing the bias-ply sizes, it seems like the difference is greater. Guess I'll have to pass. Getting even the stock tire size off the rear end, without skirts in place, is sometimes tricky already. If anyone is looking for either 6.70 x 15s or, as mentioned, L78-15s, there are two sets out on the Boston, MA craigslist stie, both sets $400 and below; two different sellers. I'm passing on the 6.70s because those are probably too small.
I have 235-75 x 15 tires on the back of my Ford. If I jack it up under the axle, the tires are a tight fit to get off or put on. The OG tires on that were an 8.00 x 14.
L78 tires haven't been made since the seventies. Those tires passed their Best Before date about the same time as the Bee Gees. I hope you don't plan on using them on the road. After 5 years tires lose half their strength whether they are used or not.
Coker sells 78 series tires. I have a set. I'm pretty sure L78. I believe my Pontiac came with 7.10X15 from the factory. All these numbers become a blur after awhile. I'm sure there is a pic of my car here somewhere with the whitewalls. Look fine.
I always thought that an L78-15 = an 8.50-15. If you have 7.60s now that would make the 8.50s 1.8" bigger. (.9" on each side of the tire) L78s were a big honkin' tire!
The 78 series tires Coker sells when I bough mine were a good bit less than the 7.whatever official size tires. If you aren't going for complete originality you might see what they are currently offering. Seems mine for less than $500 shipped brand new.
Got these Summit there Coker tires. No problem with fit I like to fill the wheel wells. L78 on the rear
Thanks guys passing on the L78s! However the Kustom gods may have just smiled on me. Found a set of 7.1 x 15 BF Goodrich Silvertowns, in my own town, for $200 with supposedly only 1500 miles on them.
I always take those tire 'charts' with a grain of salt. One thing not addressed is aspect ratio; all 'equivalent' tire sizes have tended to get smaller in diameter over the years, but have also gotten wider, so visually they tend to look smaller in diameter even if they're roughly the same size. Of course, on many older cars that extra width can be an issue so careful measuring is good. This really needs to be taken with a grain of salt. The 'tire expiration' came out of the Explorer/Firestone debacle and basically is a way for the tire companies to avoid liability. If you live in the sunbelt, there is some truth to it, but the more moderate the local tempatures, the less true it is. If you want to educate yourself, spend some time reading the DOT report found here: http://www.nhtsa.gov/Research/Vehicle Research & Testing (VRTC)/Tires Click on the first link below the 'Phoenix tire aging study' heading for the real truth.
The Jalopy Journal
