29 Dodge truck Tire size conversion

[stakeside]

Looking to purchase tires for my 29 DB 3/4 ton truck. The "DB Parts List for the Commerical 3/4 ton Truck" shows three rim sizes. They are 31X5.25, 33X 4-1/2, and 30X5. What are the conversion tire sizes? My rims are 21in. I also have a 21X5.25 Wards Tire that was a replacement tire of newer vintage.

It would be good to have a truck tread design and the prices vary alot.

Any ideas on purchase would be appreciated.

[farrellg]

The tires on my 1930 1 ton and 1931 3/4 ton are all 20". I used Vintage Tire in Hershey PA. They were extremely helpful. Gave me options based on old tire sizes converted to what was available. They also have the tread patterns online. Hope that helps.

[stakeside]

Does anybody have a conversion table for these old tires? Is the 6.25X21 and equal to the 31X5.25 or 33X 4-1/2? What is equal to 30X5?

Thanks

[farrellg]

Here is a link to one in the Universal Vintage Tire Catalog page 34. See if this helps.

https://www.universaltire.com/catalog.html

There are other suppliers, but I knew where this one was :-).

[Bob Scafani]

typically one doubles the smaller number (width) and subtracts it from the larger number (diameter) to reveal the rim diameter. Therefore 31X5.25, 33X 4-1/2, and 30X5, reveals 20", 24", and again 20" rim sizes. I don't know why there is a discrepancy for the 31X5.25.

[stakeside]

Here is a link to one in the Universal Vintage Tire Catalog page 34. See if this helps.

https://www.universaltire.com/catalog.html

There are other suppliers, but I knew where this one was :-).

See attached picture of the conversion chart. There is no 21 inch tire noted in the table. There should be 5.25X21 since I have one on a rim.

The attached page of the DB manual shows the tire size and the effect on the rear bed height. You will have to zoom in to see numbers.

I did have a conversion table but it is misplaced.

[Pete K.]

They used to measure the entire overall diameter of tire.Not just the bead size. With the few large rim sizes for sale today, we go by the tread width,(5.25, 6.50...etc...) And the rim size. In your case, 21" rims. Rims are not measured overall diameter but measured where the tire bead sits in the rim. Try a truck tire store. They may have something you like, if they still have the old tube tires!

[stakeside]

They used to measure the entire overall diameter of tire.Not just the bead size. With the few large rim sizes for sale today, we go by the tread width,(5.25, 6.50...etc...) And the rim size. In your case, 21" rims. Rims are not measured overall diameter but measured where the tire bead sits in the rim. Try a truck tire store. They may have something you like, if they still have the old tube tires!

I was able to locate Firestone 5.25X21 at Lucas Tire in Long Beach CA. The price is $173 and they are in stock. I know this correct since I have a 5.25X21 tire on my truck .