Hi I am new to this Discussion  I currently purchasing a 64 Deville convertible and It has bias ply tires that are 15 year old  they have L-78-15 tires and would like to put on radials . Question  what is a good cross to radial tire and is l-78-15 the original tire size. Thanks  Mark

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The 235/75R15 is a good match.  Look into the Ironman tires for a white wall. 

Hi Russ I am looking at the 235 75R15 in Ironman are those the RB12 after the tire size Thanks

Hey Russ   what size white wall do you recommend and what was the stock width  Thanks

I went with the ironmans, they ride well and feel good on the car. the width wall width is 1 inch. Not sure what the stock width is. 

Original white wall width and distance from rim across the 3 tire suppliers is discussed in our Tires: Original Tires and Rims (Wheels) used on 1963 & 1964 Cad...   Scroll down and you will see  chart. Help Page.

Hi Russ looked at the Ironman Tires quite a few people are complaining the white wall turns brown  after a year have you had this issue


pretty sure you are going to enjoy the driving experience that radial tires bring especially after old tires 

Lowers the car one inch -much  better cornering - braking and gas mileage ( enough?  ) 

Our Cadillacs have unique rim weights for tire balancing 

You will not ——-get your hubcaps back on with the weights the shop currently use 

I left the weights in the same location cleaned the inner rim surface and crazy glued them  to the rims lip 

That worked for me 

You should be very pleased with the results as it will be a big change in performance — the cloud 9 ride should be closer —- to back !! 


Thank you Tony, So you agree with Russ Austin the 235 75 R15 ? Have you tried stick on weights for mag wheels?

I am surprised you don't run Bias Ply on your Eldo. I am strongly considering it for my 64 Fleetwood. By all accounts I have heard, the driving feel is better than radial. Bias Ply being softer. I am not a speed runner and most of the area around here is flat- so no large concerns there. The occasional jaunt on the freeway is the fastest I ever make it. 



From my own experience the radial tire is a softer and better ride as the side walls of the tire flex more than that of a bias ply tire that is a more rigid core  design 

They absorb the shock of a pot hole more than a bias  ply tire does as an example 

Again your car - do what is best for your goals 



Bias ply tires ride harder than radials who’s sidewalls flex more than bias ply much improving cornering - less rolling resistance equals better gas mileage — better stopping power 

There are a good number of other benefits with 50 plus years of tire technology improvements behind redials 

All new modern cars are on radials from the showroom 

I am old enough to remember when all cars came with bias ply tires new so have experience with both first hand 

Coker makes a tire that looks like an older bias ply tire ( if looks is your thing  ) and are radial tires but they are expensive 

Hope that helps some 


Do not recall my tire size at the moment but Russ is as good as it gets regarding our year Cadillacs  info 

So yes 




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