Authenticity vs Safety

[CMP-Phil]

Tire question - Does anybody know of tire information source that shows actual tire diameter to size for given time periods. The issue is a 8:20 x 15 Supper Balloon of the late `40s early `50s is not necessarily the same diameter as a modern 8:20x15. Guess any chart would also have to include the rim width. Done some searching on the web but have found nothing that provides dates only comments that they are different so far.

What I'm trying to match is the both the look as well as the ground clearance of the original tires.

Cheers Phil

[Barry Wolk]

I think the P235 would be your only choice because of the load rating. I have Coker 3" whitewalls and it's been in 50 Concours and it's never been dinged for tires.

You can also take a proper tire and have whatever size whitewall you want. I have Diamondback tires on my Porsche. I found some skinny European Michelin X tires in 16" and had a factory-correct whitewall applied. The tires balanced beautifully.

[autostick]

Tire question - Does anybody know of tire information source that shows actual tire diameter to size for given time periods. The issue is a 8:20 x 15 Supper Balloon of the late `40s early `50s is not necessarily the same diameter as a modern 8:20x15. Guess any chart would also have to include the rim width. Done some searching on the web but have found nothing that provides dates only comments that they are different so far. What I'm trying to match is the both the look as well as the ground clearance of the original tires. Cheers Phil

I guess you Google searched 8.20x15 diameter and have seen these results:
http://www.turbinecar.com/tires.htm
The 8.20-15 is 29.50 outside diameter and the 235/75R15 is around 27.875 outside diameter.
Call Fritz's tire in Maine, the guy can tell you everything you want to know and he's a DBTire (whitewall tires) dealer for over 40 years. http://www.jalopyjournal.com/forum/show ... p?t=650783
http://www.jalopyjournal.com/forum/show ... p?t=418035
http://www.imperialclub.com/Repair/Wheels/size.htm
Each of these URLs say the actual tire diameter but since you Googled that already I suspect I don't understand your question, what do you mean by "found nothing that provides dates only comments?" A given tire size does not vary over time.

[CMP-Phil]

Hi Barry and Autostick

Thanks for information and the links, they help nail down the size issue.

What I meant when I said " Done some searching on the web but have found nothing that provides dates only comments that they are different so far." is that most of the size charts I could find didn't give a date for when the chart was done. One of the charts you point out shows the change in size depending on date



One of the reasons this question is coming up is that when I first got this car back in college 1969 it needed new tires and I bought the "same" 8:20-15s as what was on it. Though the numbers stamped on the side wall was the same the tires were new tires were significantly smaller. Which the above chart shows in 1969 I should have been getting 9:00 x 15s.

I had a similar problem with 190SL so now when matching tires I really try to research the diameter of the tire and side wall height.

What I have not found yet is the actual measurements of 1949 Firestone 8:20-15s as used on the 1949 Lincoln Cosmopolitan as delivered. Of course now I wish that I had kept the original spare tire that was in the trunk when I got the car back then, but I figured a 20 year old tire was probably not a good spare.

Thanks for the help, you have given me an idea to modify my search, think I'll try to find a 1949-50 tire catalog see if it list sizes and dimensions, failing that maybe a 1950 wheel alignment manual would have the info.

One of the funny lines I find in most of the online sources is that they say the tire dealer has this information, well I haven't found a tire dealer that actually has the data, they just say they have the right tires for my car.

Cheers Phil

[linc64]

Phil, maybe someone on the AACA forum would have the info for you.

http://forums.aaca.org/forum.php?s=86d3 ... 8138604ce9

[CMP-Phil]

Hi Jim

Yes, it looks like AACA may have a tire manual with the information wanted in their library. I'll give them a call next week to get more information.

Cheers Phil