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Tubeless radial tires on a 1941 Cadillac?

Started by lt morty, June 20, 2013, 08:11:10 AM

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lt morty

Has anyone tried tubeless, radials on old oe wheels ("j" rims) for a 1941 Cadillac, or similar?

I have found tubelss radials in 7.00x15, but would like to learn from others experience before buying.

Thanks
Morten
1941 Cadillac Series 61
1944 Ford GPW
Bantam trailer

Bill Ingler #7799

Hi Morten: Once you drive your 41 with radials you will never go back to a bias tire. I had the 700x15 Diamondback radials on my 41 and also on my 47. Many thousands of miles on these tires and no problems. The radials are mounted on the original wheels that came with the car from the factory. The wheels hold air and I have never had a problem with losing air. A couple of times a year they would need a couple of pounds of air. The 700x15 used by Diamondback was a Yokohama light truck tire. I use 35 pounds of air which makes for a comfortable ride. I always have the wheels sandblasted and then make sure there are no pin hole rust spots, then powder coat the wheel. If you do buy from Diamondback make sure you get the tire with what they call the beauty ring which is a raised white rubber ring separating the white on the side wall from the black. I am not familiar with what you call a j wheel?  Bill

http://www.dbtires.com/

Caddy Wizard

Bill's tire recommendation is right on.  That 700R15 tire from Diamondback is absolutely the best tire you can put on one of these old cars!  It looks like a bias-ply, handles like a radial and steers with minimal effort due to its very narrow tread patch.  Really, it is the best of all worlds and obviates the need for many to add power steering to an old car that didn't have power steering.


I have had these tires on my cars and just loved them!

Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

lt morty

Thanks for sharing Your experiences.

The tires on Your pictures sure looks very much like the Yokohama RY 215 they sell on tirerack. Tirerack states this tire as 7 R 15 LT.

Has somebody tried them on their original rims? I would like to find a blackwall tire...

Just so I get it wrong. Does somebody rember, or have their shop manual handy... What is the rim with on the original wheel? 5 or 5,5 inches?

By the way, with "J" rim i refer to the outer lip on the rim beeing bent like a J, and not having the safety rim on the inside of the wheel to hold the radial wheel in place in case of a sudden loss of air...
1941 Cadillac Series 61
1944 Ford GPW
Bantam trailer

Raymond919

Quote from: Art Gardner  CLC 23021 on June 20, 2013, 11:49:14 AM
Bill's tire recommendation is right on.  That 700R15 tire from Diamondback is absolutely the best tire you can put on one of these old cars!  It looks like a bias-ply, handles like a radial and steers with minimal effort due to its very narrow tread patch.  Really, it is the best of all worlds and obviates the need for many to add power steering to an old car that didn't have power steering.


I have had these tires on my cars and just loved them!

Art, if I understand correctly, I can put this tire on my car in place of the 8:20X15 (L78.15) and it will have the same weight bearing capacity as what the factory calls for? I'm planning long range to buy radials and am concerned about choosing the correct tire. Those P225/75R15 just seems like a lot of tire and I'm concerned about the lack of power steering, clearance with my fender skirts, and whether or not the front wheels will contact the inner fender or suspension components when turning. I have a '49 4 door sedan, series 62.
Do you also know if these smaller tires from Diamondback are priced less than the P225/75R15? I'm working on a budget and have been saving for these tires.
Many thanks for whatever guidance you can offer.
Ray Schuman
#26141

Bill Ingler #7799

The correct Cadillac wheel width for the 700x15 tire used on 41-47 was 5.50 inches and 5 inches if using a 7.50x16 as on a series 75. In 48 the width of the wheel was increased, to I think 6 inches, too accommodate the wider 820x15 tire. Now be very careful and make sure that you have the correct width  41 wheels so when you put on the correct 41 cap, the retainer ring on that cap will hold on that wheel. Since the 48 wheel width is wider to accommodate the 820x15 tire, the 41 cap retainer will not seat down far enough on the 48 wheel, then the cap can fly off the wheel. More than one 41 cap has been lost if it is on a 48 wheel by simply hitting a chuck hole or taking a corner too fast. Off comes the cap and if it is a rear cap then your chances are good the flying cap will also take out the fender skirt which in turn can dent up a fender.   Bill

Raymond919

Hello Bill,
I guess I have some learning to do. My wheels are rated as 6 inches. I've never actually measured them but assumed they were correct. I guess I'll have to physically measure them to ensure they are correct. My car is a 1949 not 41. When you refer to a 41 or 48 wheel, is that a model number or size rather than the year? What is the cap you refer to? And what is the cap retainer?
Ray Schuman
#26141

Bill Ingler #7799

#7
Hi Ray: If your wheel width measure 6 inches from bead to bead then you have a wheel size of 15x6 which is correct for the 49 wheel. From 41 through 47 the Cadillac wheel width measured 5.50 inches from bead to bead and the wheel size was known as 15x5.50. The wheel cap that I am referring too is the sombrero cap which was introduced with the 47 Cadillac and I believe was used through 52 and it might have been through 53. Now there is a difference between the 47 sombrero hub cap and the 48-53 sombrero hub cap. The retainer ring on the sombrero cap is a ring that is riveted to the back side of the cap and this retainer ring fits into holding clips fitted on the wheel. Now there are 2 ways to identify a one year only 47 sombrero cap from the 48-53 sombrero cap. Measure the depth of this retainer ring and it will measure 2 -1/4 inches on the 47 cap and 2-1/2 inches on a 48-53 cap. The easier way is to count drain holes on the retainer ring. On a 47 sombrero cap the retainer ring will only have one 1/2 inch drain hole while the 48-53 sombrero cap will have two 1/2 inch drain holes in the retainer ring. The 2 drain holes will either be side by side of 180 degrees apart from each other. Now these sombrero caps have been reproduced by several sources over the last 20 years and I presume they kept the specs of the original caps the same in the repro caps. I have tried to stay with original caps so I can`t be sure if the repro caps used one hole on 47 and 2 holes on 48-53 caps.

When I switched from bias ply tire to radials on my 47 I was concerned that the P235/75R15 would be two wide a tire and would rub the fender skirt or come very close. I then called Diamondback I think when they first started to make the 700x15 radial and talked with Bill who I think started the company. He said the 700 X15 radial he offered was only 1/8 inch wider from side wall to side wall than the original 700x15 bias tire that came from the factory. So the 700x15R is what I have on my 47. Now the original size tire for your 48 was a 820 x15. If you look at the Diamondback web site it will show that the Diamondback 700x15 radial is also used as the replacement radial for the 820x15 bias tire. If I were you before you decided which tire and size to buy, call Diamondback and talk with them about the best tire and size for your 49. Hope this helps.   Bill

TonyZappone #2624

I used the slightly wider version from Diamondback than the Yokahoma.  They were less expensive and at the time I was buying three sets, one for the 41, one for the 47 and for the 58.  Bill Ingler is right about the beauty ring.  I don't even know why they sell them without.  No problem with holding air.  The only problem I had with the wider tire on the 41 and 47 was slightly rubbing the skirt.  Five minutes on the bench grinder for each skirt readily adapted the skirt.   I think these tires have been on these cars over ten years now (the 41 is sold).
Tony Zappone, #2624
1936 Pierce-Arrow conv sed
1947 Cadillac Conv cpe
1958 Cadillac conv
2016 Cadillac CT6 Platinum
2022 Chrysler Pacifica Pinnacle

dino

I recently installed a set of  700x15 Diamondback radials on my 47.  Not cheap but worth it.  Best thing I ever did..  Spend the money and get the right tires..
D.Martini
1954 6237DX  CDV
1956 6267X  CCP

1960 6267X  CCP

The Tassie Devil(le)

Don't forget to have a wheel alignment performed to cater for the new tyres.

Radial Tyres have different alignment to Cross-plies.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

bob48cady

      Hello, I have been running 235/70R15 radial tires on my 1948 Cadillac for the past 23 years and they work great. I don't have any rubbing problem or air leakage problems. I am running the small cap with the beauty ring on stock rims. Radials tires ride so much better then the old bias ply tires and don't wander on the road either. I don't have any problems with the car steering hard in a parking lot as long as I don't try to turn the wheel at a dead stop. Thanks Bob Stahl
Bob Stahl
      Affordable Motorcycle Repair LLC.

Raymond919

Quote from: Bill Ingler #7799 on June 21, 2013, 12:44:32 AM
Hi Ray: If your wheel width measure 6 inches from bead to bead then you have a wheel size of 15x6 which is correct for the 49 wheel. From 41 through 47 the Cadillac wheel width measured 5.50 inches from bead to bead and the wheel size was known as 15x5.50. The wheel cap that I am referring too is the sombrero cap which was introduced with the 47 Cadillac and I believe was used through 52 and it might have been through 53. Now there is a difference between the 47 sombrero hub cap and the 48-53 sombrero hub cap. The retainer ring on the sombrero cap is a ring that is riveted to the back side of the cap and this retainer ring fits into holding clips fitted on the wheel. Now there are 2 ways to identify a one year only 47 sombrero cap from the 48-53 sombrero cap. Measure the depth of this retainer ring and it will measure 2 -1/4 inches on the 47 cap and 2-1/2 inches on a 48-53 cap. The easier way is to count drain holes on the retainer ring. On a 47 sombrero cap the retainer ring will only have one 1/2 inch drain hole while the 48-53 sombrero cap will have two 1/2 inch drain holes in the retainer ring. The 2 drain holes will either be side by side of 180 degrees apart from each other. Now these sombrero caps have been reproduced by several sources over the last 20 years and I presume they kept the specs of the original caps the same in the repro caps. I have tried to stay with original caps so I can`t be sure if the repro caps used one hole on 47 and 2 holes on 48-53 caps.

When I switched from bias ply tire to radials on my 47 I was concerned that the P235/75R15 would be two wide a tire and would rub the fender skirt or come very close. I then called Diamondback I think when they first started to make the 700x15 radial and talked with Bill who I think started the company. He said the 700 X15 radial he offered was only 1/8 inch wider from side wall to side wall than the original 700x15 bias tire that came from the factory. So the 700x15R is what I have on my 47. Now the original size tire for your 48 was a 820 x15. If you look at the Diamondback web site it will show that the Diamondback 700x15 radial is also used as the replacement radial for the 820x15 bias tire. If I were you before you decided which tire and size to buy, call Diamondback and talk with them about the best tire and size for your 49. Hope this helps.   Bill
Bill, thank  you so much for the education. I've learned so much! How stupid of me not to realize that the 'cap' referred to the Sombrero wheel cover (which I have). I will definitely speak with Diamondback before just going ahead and ordering tires when I'm ready (which I hope will be soon). I was also surprised by the comment by Tony Zappone of his grinding off a small bit from the fender skirt. Stupidly (again), I never considered that an option. It's very clever!
I want to go to radials since I drive my car so much. I want the car safer and easier to handle.
Once again, thank you to everyone here in the forum. It's like going to school and learning about various aspects of automobiles. I read every posting whether it pertains to my car or not.
One last question. Next to a poster's screen name on the left there usually is a small picture of their car. How do I enlarge that image to see the car better?
Ray Schuman

R Sotardi #11719

Lots of discussion in the past. Raymond, How much do you plan on driving your car? Our chapter just had a tech talk from a well known Discount Tire manager, who is also a hobbyist . Radials are great on cars that are used frequently, however radials should be rotated OFF and replaced well before 8-10 years and have a kind of memory from sitting. Please go to a tire shop and inquire. Pick their brain. Discount Tire has a working relationship with Coker and can order any thing that Coker sells. Many countries don't even permit radials over 6 years old. That can be pricey. A few years ago a friend was cruising right along in front of me in his '38 with radials, when his big right rear wheel cover came flying off. I stopped, picked it up and brought it home to him...his lucky day.  Ron

Jay Friedman

Ray,

Art Gardner, one of the earlier posters on this thread, had Diamond Back 700 x 15s on his 1950 Series 62 4-door which worked great.  (He lives near me so I know his cars well.)  As Bill Ingler pointed out, your 49 Series 62 has the same wheels as a 50 Series 62 so there should be no problem using those tires. 

Check with DB as they are expensive, $240 each or so.  You can get them as blackwalls from Tire Rack for $170. 



1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Raymond919

Once again, thank you all for your responses and great information.
Ron, I bought the car just under three years ago and have driven it over 10,000 miles. With new radials on the car, I suspect I'll easily do around 5.000 miles per year. I'm having a ball with it. During the winter months, if the ground is wet or there's salt on the roadway, I just move the car a couple feet forward or back in the garage to eliminate flat spots. When I first got the car the tires were almost square from sitting. It took a long time for them to get round again.
I definitely will ask questions at a tire shop but financially, I haven't reached that point yet. I can see it happening before next Spring, however. It's been stated about certain companies having a bad reputation with their tires but I don't  know if the stories are true or not. I've heard Diamondback is very reliable  and have decided to eventually go to them.
Jay, both you and Art have given me great advice through the forum and directly during the past three years and I thank you publically for that. As for the cost of the tires, I expected them to cost about $250 or a bit more. I've been told to expect about $300 once all costs are included such as shipping, taxes (if any), mounting. I would definitely get wide white walls about 3 1/8 inch. That just looks like the best size to me for my car. I think that I read someplace that the 700X15 tires are actually truck tires accounting for their increased carrying capacity. Not sure how true it is but sounds logical to me.
Ray Schuman

Bill Ingler #7799

#16
Ray: Yes the tires were produced as lite truck tires.The two sets of Diamondback 700X15R I have bought were marked Yokohoma LT tires and are 8 ply. Marked with a max pressure of 55lbs but as I said in an earlier posting, I carry about 35lbs which gives me a comfortable ride.    Bill

On your question about enlarging the small picture next to a posters name, A forum administrator will have to answer that question. If you see a car that you like, send the poster a message through this forum that you would like a picture of the car and I bet you get a nice picture in return.

lt morty

What a great forum this is!

A lot of good advice here.

I've ordered the Yokohamas as I want blackwalls in my 41. Not many cars had WW tires back then.

Following Your advice I will have the wheels blasted and painted before I mount the new tires.

And now I know what to do this winter: overhaul the suspension parts and have all wheels aligned. Just to be sure.

Thanks to everyone who has contributed in making this tread so interesting, and usefull.

Morten
1941 Cadillac Series 61
1944 Ford GPW
Bantam trailer