Can someone tell me what is the largest size tire one can fit to the old style ('36 20") wheels?
ron

7:00x20 8 ply on front and 32x6 10 ply on rear were the largest tires for gross load range 11,300 to 13,300 lbs. (dual rears) that Chevrolet had as options in 1936. Spacers were required on rears for duals. You would also need to use the 6 inch wide rim.

What I meant to ask was; from anyone's experience, what is the largest tire they've been able to squeeze onto the original 6" rims.
ron

Ron,
My truck has 7.00s all around. They look too big on the front and they rub when I turn hard. I'm planning to replace them with 6.50s.
I do not know what the rim width is. My outside wheels on the rear do not match the other four wheels but I have not measured the offset or width to see if they are dimentionally correct even though the appearance is different. The 7.00s look fine on the rear and there are no clearance problems of any kind. 7.50s would probably fit there but would look out of place and definately be too big for your 6 inch wheels.
If you are just looking for somehing to roll around on, you can cheat a little, but if you are planning to hit the road, I would not want anything larger than 7.00s and expect them to rub like mine when you turn the front wheels hard.

Mike

Chevrolet did have an option (1936) of the 7:00x20-8 ply on the front but you had to have p/n 602012 wheel 6 inch wide with a 4 & 11/16 inch offset

OK guys, thanks. I'll see if I can cram 7.50's on the wheels; just looking for a little more speed. The enclosed drive shaft doesn't make it easy to put an overdrive in there.
ron

Is your truck the 131" wheel base or the 157" wheel base? Chevrolet made the set up of the drive line with the removable intermediate torque tube so that vendor commercial units (such as over drives, transfer cases) could be installed.

I have the 131" model. Since the intermediate shaft is enclosed I thought there would not be an easy installation of a three speed behind the four speed. Any suggestions? Thanks.
ron

The intermediate shaft is a short 16 & 3/8 inches long with a universal joint on both ends and a support bearing in middle. The system allows the transmission & intermediate shaft to be removed without having to loosen the rear end. It would take a lot of work to get an overdrive unit in the space but it could be done.

Hi Ron,
In the 37 Silver book, Budd offers 9.00 X 20 option. OK for your bus but wouldn't have room in rear for duals. 7.50 duals would fit in rear. 7.00 X 20 is as large before hitting fender in front. .
. You probably have a 6.17 or 5.43 ratio torque tube. (All ton & half from 1931 - 2003 had only these 2 ratios.) Look at web page <http://home.znet/c1937/RPM.htm> for speed with different size tires. You want the RPM at 60 MPH to be 2000 to 2500, depending on engine. . . .
. Call or Email me for a list of Overdrive vendors. The guy in Healdsburg won't work on anything but model A torque tubes any more. A Clark doesn't offer much of an OD and a Brownie needs to be cushion mounted on frame to avoid gear noise.
Also ask for picture of Brownie in torque tube in 37 Log truck at Spokane. . .
. Good luck, Lou

Muchas gracias Lou. Cool chart, pretty tells it how it is. I'll probably go with the 7.50.
ron

Ron,
I was out working on my '36 truck today. I took a closer look at the rear wheel situation. The "odd" wheels I mentioned in my earlier post have more offset than the other four original wheels. The 7.00 tires on the duals would rub or nearly rub one another if not for this extra offset. They appear to be about 1/2" wider (rim) and with about 1.5" more offset than the other 4 wheels.
Mike