Fit of 11x20 tires on M35A2


Rear tires
There is 1.25" clearance between the tires except at the bottom where it is right at 1" due to normal tire bulging. the image is affected by a distortion in the camera lens that makes the wheels seem to lean together at the bottom. This can be verified by seeing the centerlines of the tires.
This view is taken from the 1 o'clock position, looking down to the ground. the brown matter is some old leaves, etc. as can be seen there is plenty of clearance. The aspect ratio makes it look closer, but nonetheless..
another shot, this one from the 12 o'clock position, shows the clearance.

The truck is a 1968 M35A2 with a S-280 type shelter in the bed (image). The total weight of the vehicle is 19660 lbs. The empty weight is approximately 14000 lbs (the 11.00x20 tires are slightly heavier than the 9.00x20 tires, and add about 500LBs to the weight). The load on the bed is approximately 5660 lbs., and consists of the shelter full of communication gear and several days worth of emergency and field supplies.

The rear tires are new surplus Titan T-Hawk 373's. Load range F, 12 ply rating, 5190 LBS in dual at 75 PSI cold, 11.00x20 Military. 90% of my driving is over-the-road, so I would seldom, if ever, deflate the tires. I run 60PSI in the Titans.

NOTE: Just because these fit, don't asume any 11.00x20 NDT will fit the truck! Some people have reported that the tires they tried are too wide, and will rub. If they rub, they will heat and fail catastrophically (explode). It was also suggested that 'older' tires tend to bulge more. Another point was made, to ask "What happens when you deflate them somewhat for offroad use?" It is not yet known what all the answers are, or what differences there may be between brands of tires. If in doubt, mount up two on a dual and see how much clearance you have. If you don't have at least 1" at the closest point (at the bottom) with the truck loaded as you will use it, don't risk it. As a reference point, I had 1.75" of clearance (at the top and sides) with the original 9.00x20 tires. I will not be deflating the tires, as the vehicle is used on relatively firm ground.

Front tires:
The original 9.00x20 NDT military tires on the front of truck, after 4000 highway miles, were worn nearly bald. Even when they were like new, they were never very good on wet pavement and did not seem to grip the road well when it was bumpy. Since I do mostly on-road driving and drive about 1500 miles every year, I have replaced them with Toyo Hyperadial M140Z 11.00R20 'steer tires'. These are designed for use with tubes and split rims, and are rated at 7390 LBS each tire at 120PSI. These are made for commercial tractor trailer use. Initially, I put 80PSI in them, and found that the M35 steering is much easier. Unlike the NTD military tires, these are supposed to offer better steering control on pavement and much better tread life (especially on this 'light' truck). Notice the radials bulge quite a bit where the tire rests on the pavement. I would not reccommend them as duals in the rear positions. The radial tires cost about $300 each. Bias-ply tires would have been more like $175 each.

1100R20_1.jpg 1100R20_2.jpg 1100R20_3.jpg

Here are some notes on tire sizes, RPMs, and speed.