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41-47 radial tires- need advice

Started by G Pennington, May 20, 2016, 04:06:37 AM

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G Pennington

(reposting as new topic)
My recently acquired '41 6267D has Coker 700x15 bias-ply tires.  Two of the tires are 16 years old and need to be replaced.  Was thinking about replacing all 4 with radials as this is primarily a driver and not a concurs car.  On the advice of others on this forum, I ordered a catalogue from Diamondback with the intent of buying a set of radials.  Was surprised that the 700R15 (Yokohama) was not listed.  Contacted Rich at DB and he said he could still get them, but that they were actually an 8-ply truck/trailer tire.  He assured me they would ride much better than the Coker bias-plys, but if I was REALLY concerned about ride quality, I could order the 235-75R15 "DB II" tires.  Problem is, the section width  on the DB II 235-75R15's is 9.1" vs. 7.8" on the Yokohama 700R15's, and I am concerned about clearance, the way the car will look, and also the steering effort.  Diameter is about the same, so no problem there.
Any advise?  Also, what width whitewall is correct for '41?
Gary Pennington
   1953 6267X Convertible
   1941 6267D Convertible (2 door)

Bill Ingler #7799

#1
Hi Gary: I started about 15 years ago with the Diamondback 700x15 Yokohama radial. As Diamondback will tell you the Yokohama is an 8 ply  light truck tire with a 55 lb recommended tire pressure. No way was I going to ride around in my car at 55lbs with a hard ride. I experimented with different pressures as to ride and most important of all, what was the side wall profile of the tire at these different pressures. Pictures below are of my 47 convert at 50, 40 and 37 pounds tire pressures. A good ride was found at 37 lbs and what I consider a normal side wall profile. I settled on using 35-37 lbs and before I sold the 41, I had the car on two CCCA tours and enjoyed every mile with the radials. My 47 has been on more CCCA tours and still I have had no problems with the tires.   Bill

Carl Fielding

By all means go for the L.T. tires. Radial tires operate perfectly well over a very wide range of pressures , according to conditions. Load , speed , road surface , temperature , are factors. Radial tires have a greater range in which you can tune your suspension for comfort , handling , and safety. The high pressure L.T. radial might give you a soft "Cadillac Ride" at in town speeds of , say 30 - 40 mph in the mid to high 20s of psi. This will give you max protection from potholes and other occasional road surface irregularities encountered on city streets. At sustained high speeds on a well maintained Interstate , you could enjoy the handling and economy achieved at pressures well into the 40s. Bill has found the sweet spot for general mixed use for these tires. I have been using radial tires for over 50 years under all conditions , both on and off road , FWD , and RWD , 4-WD , and AWD. Stock , and modified. At this point I don't want to delay your purchase by drowning you with TMI. Ask me sometime about radial tires doing extreme duty under every conceivable condition all over North , Cantral , and South America. You will LOVE tuning your L.T. radials for conditions. You will also love them if you just leave them at the pressure Bill has already worked out for you. Go get 'em !  - Carl

Jay Friedman

Carl, I found your discussion useful, as I'm contemplating changing to Diamond Back radials on my '49.  However, I'm not familiar with 2 of the expressions you used: 1. "L.T. tires" and 2. "drowning you with TMI".  Can you clarify, please.
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."

Cord1930

Hi.  Has anyone considered the American Classic tire as a replacement to the bias ply for the 1941?   This tire has the look of the bias ply but is a radial. The closest size to the 700-15 is the 820-15, (for overall height, load, and tread width), I know that it is recommended with a wheel 6-6.5 inches.

BillR. CLC # 29203

Jay,
I can help you out with TMI...Too Much Information.
As for the LT...I have no idea and am waiting to hear what it is.
BillR.
Bill Rodwick
CLC # 29203

Crew Member:  '59 Sedan Deville Six Window

Steve Passmore

Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

Bill Ingler #7799

#7
You have to be careful of the width of a radial tire when mounting the tire on the 41-47 wheel and then using that wheel/tire on a 41-47 Cad. The 41-47 wheel is 5 & 1/2 inches from bead to bead. In 1948 the width from bead to bead was increased to 6 inches to accommodate the new 8:20x15 tire. The American Classis tire might work on a 41 but before I would buy I think you need to know the profile width to check for clearance. I know the tire clearance on a 47 rear fender skirt is a must check before using any radial tire. If a wider wheel is used for the radial, then in addition to checking profile width you need to check clearance of the wheel cap to the skirt. Bill 

Carl Fielding

Correct , guys. Light truck radials are superb for our heavy Cadillacs. Just be careful after running them aired down for comfortable city driving conditions. Out on the highway , they must be brought up to higher pressure. Anyone who has had to endure my often verbose soliloquies will understand why TMI can be my stock in trade. Keep a "hook" handy to drag me off my soapbox ! My youthful foreign driving adventures are quite entertaining , however , according to various audiences. I am incredibly lucky to have done this while strong and able. Radial tires are so superior that in my OPINION they should be encouraged , and exempt from any penalty in judging. I love driving , and still do it. I think there are plenty of trailer queens (which I also love) which ride on bias ply just to show us how they were. Driving should be done on radials , and many of us drive our cars every chance we get. Again , my OPINION.  - Carl

Jay Friedman

While I realize radials are superior, I've been driving my '49 regularly for 30+ years on 8.20 x 15 bias plies with no major problems.  They ride fine until they get worn somewhat which, of course, happens more quickly than with radials.  The only problem I've encountered while driving is the well-known tendency they have to sometimes make the car wave a bit from side-to-side at higher speeds when the road is worn from heavy trucks.  I still have bias plies for no particular reason except inertia, and also because until recently radials were much more expensive.  Now that they cost about the same, I'll probably switch to radials, most likely Diamond Back-Yokohama 7.00 x 15s.

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."

marty55cdv

Quote from: Cord1930 on May 20, 2016, 03:17:50 PM
Hi.  Has anyone considered the American Classic tire as a replacement to the bias ply for the 1941?   This tire has the look of the bias ply but is a radial. The closest size to the 700-15 is the 820-15, (for overall height, load, and tread width), I know that it is recommended with a wheel 6-6.5 inches.
I have the Bias Look alike on my 41 Fleetwood,  the closest tire to 700-15 is the 710-15 in that tire, the
820-15 I believe is close to a 235-75-15 which is too large for a 41.   I had radials on my car already but they were quite old and were wider than they should of been, putting on the narrower correct width made my car feel like I had power steering, I noticed the second I started to back out of the garage, they look great and ride just fine. 
Marty Smith
  CLC #22760
41 60 Special http://bit.ly/1Wm0GvT
55 CDV http://bit.ly/1G933IY
56 Fleetwood
1958 Extended Deck http://bit.ly/1NPYhGC
1959 Fleetwood  http://bit.ly/1OFsrOE
1960 Series 62 Coupe
1960 Sedan DeVille  4 window Flattop
63 Fleetwood http://bit.ly/1iSz17J
1964 Eldorado http://bit.ly/1Wm17GA  (Living in California now)
1988 EBC http://bit.ly/1iSACKz

Carl Fielding

Well , I just had another creative , informative masterpiece wiped into the cyberdump. Bottom line was , don't worry if your rim width is said to be too narrow for a given radial. It will work just fine. For the rest of my TMI dissertation , you will just have to come talk to me if I live long enough to get my off-road modified '71 Eldo droptop to a G.N. It will be the only Cad that looks like a piece of military hardware that fought on the losing side of World War Four. But man that car worked well all over Mexico , Baja , and domestically as a hunting rig. 33" B.F. Goodrich Radial All Terrain T/As on stock rims. All it does now is blow minds on the rare ocassion it gets out. Yeah , don't worry about rim width , O.K. ? - CC

G Pennington

Looked at the 710R15 American Classic (Coker?); only complaint is that it's only available with a 2 3/4" whitewall (1941 authenticity manual specifies 3 1/4").  The Diamondback/Yokohama 700R15 is available in any WW width.
Gary Pennington
   1953 6267X Convertible
   1941 6267D Convertible (2 door)

denniscaddy

Hi all, and Jay, too!

When I first restored my 55 Eldo, I put on bias ply tires, for the look.  They didn't wear well, and the car wallowed terribly.  I replaced them with Diamondback radials, and the results were excellent.  When I put a set of Diamondback radials on my '49, I simply couldn't believe the change in the handling;  it was like a different car.

I just had a set of Diamondbacks put on my '41 60S.  They look like bias tires and ride and handle like radials.  They are terrific tires in my opinion.

My experience tells me that the radials which look like bias ply are the way to go, and I've had great luck with Diamondback.

Dennis, CLC 3676
CLC 3676
1941 Fleetwood 60S
2017 CT6

Mike Wenrich #1666

I don't believe anyone said the Diamondback LT Radial will work with a 1941 that is running fender skirts.  It looks to have the correct width/profile and correct of white wall.  It might be narrow enough but I sure would like to hear they will work with the skirts before buying them.  I have the stock wheel width. 

Bill Ingler #7799

Picture below is my 41-60s with Diamondback Yokohama  LT 700X15 Radials. Here is a friends 41 sedan with the same tire. No problem with skirt clearance on either car.  Bill

Mike Wenrich #1666

Thanks Bill.  I will have to look for the best way to get five of these on the west coast before they are gone. 

Mike

G Pennington

Thanks for all of the advise.  Looks like I'll be going with the Diamondback/Yokohama LT700R15's.  Just found out the PO was running tubes in the bia-plys currently on the car.  Should I run tubes with the radials?
Gary Pennington
   1953 6267X Convertible
   1941 6267D Convertible (2 door)

Bill Ingler #7799

Gary: I bought my 41 in 1995 and my 47 in 1985. Both cars have many miles on the Diamondback LT Yokohama radials without tubes. I have been told from the beginning that tubes are not needed and if you do run with tubes it will cause heat inside the tire which you don`t want in a radial. Due to the high heat in Phoenix, starting about the last of May when 105-110 is what we have for 3 months, most old cars stay in the garage. I drive with 35-37 lbs and after sitting for about 4 months I probably am down about 5 lbs per tire. I am fortunate that I have a Discount tire store down the street and they mount and maintain all my old car tires. Using the correct valve stem when mounting the Diamondback on my wheels has never been a problem with Discount Tire. Enjoy driving on your radials and you will never go back to a bias tire.  Bill