I too have been looking for stock size radial tires for my 1952 GMC 1/2 ton, which is currently undergoing a body off restoration. When I purchased the truck, it came with old BF Goodrich Silvertown bias ply tires in the standard 6.00X16 tires on the front and 6.50X16 traction tread tires on the rear. I want to keep the original look but everything I have read here points to the superior driving characteristics and safety of the radials. My only concern with some of the radial tire sizes recommended by others here is that the tread width is much wider than the original tires, which increases the low speed steering effort.
I measured my original BF Goodrich bias ply 6.00X16 tires which are currently mounted on my 1950 Chevy 1/2 ton as I wanted to see how they look and drive. (When I purchased the Chevy, it had 215 75R15 and had very heavy steering effort when trying to park it, but drove with little effort at normal driving speeds. Now steering effort at low speed with the 6.00X16s is like driving with power steering compared to the 215/75R15s.)
The 6.00X16 tires measure a little over 27" in diameter mounted on the truck with a tread width of 4.63". I measured the diameter with the same tire off the truck and it was a little over 28". Compare this to the information on Coker Tires website where they give the following tire dimensions for their BF Goodrich bias ply 6.00X16: diameter - 28.3", section width - 6.25" and tread width of 4.63 " The 6.50X16 bias ply traction tires on the rear of my truck measure about 28.5" in diameter with a tread width of 5.88".
Diamond Back Tires has a radial tire that matches up closely with the original tire dimensions. Their information is as follows for their 195/754R16: height - 27.7", tread width - 5.4", section width - 7.6" and their 205/75R16 is slightly larger. Coker tires does not give a metric designation but instead gives the following dimensions for their Excelsior Stahl 6.00X16 radial: diameter - 28", cross section - 6.5", tread width - 4.6".
Tires from these two companies are not cheap at over $200 each plus shipping and local mounting. I still haven't figured out their controversy on whether or not you should use tubes with their radial tires. Diamond Back is states that you should not use them while Coker recommends them, adding even more to their cost. I haven't figured all this out myself, but hope this at least helps with your question as to what radial tire size matches up to the stock size tires.
