GMC 353 (orig.7.5x20) on M35A2 9.00x20 tires

How are the 9.00x20 looking at the GMC?Could anybody post a picture from a GMC having it....Thinking about it, because I have 11 good M35A2 tires there, they are 3.5" highter.Now having the bad not original US Army Omaha style looking tires from the Army of Norway

the 9.00 x 20s will fit but you have to put them on the CCKW wheels. if your doing a restoration IMHO you should go ahead and get the correct 750 x20s. the CCKW does not look right with the fat tires. I njust bought 12 750 x20s for my 352 open cab. $168 USD per tire.

7.50-20 is a standard tire size. If you not insisting on the original tread pattern, there are many tires available which do last much longer than the original on road use and there are modern tires which have a much better off road performance than the original pattern, for example tipper tires.
9.00-20 tires might get in contact for the boogy whell base is probably a little to small for these tires. As used by the French Army, 11.00-18 on a standard CCKW 353 / 353 needed singles rear due to tire contact. The DUKW boogy is adjusted for the 11.00-18, so there it works.
Wolf
At least the rim offset is to small for 9.00-20 tires and so the tires will get damaged.

IMHO, the following truck is awesome (with 9 x 20s) but I do love the look of the 7.5s. Maybe the owner is a member, and can chime in.......either way the CCKW is a good looking truck. The "model" is my 4 year old daughter......I'm trying to boost the SS membership!!!!

They will fit with caveats... first is front tire rub. Unless you adjust your knuckle limit bolts you can rub the tire on the frame. Second is as noted the rear axle spacing is gonna make loss of 3 inches kinda tight (technically if they are not touching you should be OK but if you go off road and get the rear bogey in a steep angle you'll start rubbing the bed.

I would think more importantly is that you are gonna gear up the truck a bit. 1st gear is really only good to like 3-4 MPG on 7.5 x 20s... I doubt that you'll go that fast with taller tires (engine is gonna have to spin more to turn the same tire RPMS). If you have a working governor your should be OK (if it truly works). The reverse is also true on the double clutch... you'll have to rev it higher to catch the tranny due to larger diameter. Braking will also suffer as the tire now has a longer lever arm against the brakes. So slowing down is gonna take even longer.

As for 'originality' yes, from the factory NDTs were specified. In service it was not uncommon for a cckw to only have 8 or 9 wheels (tire shortages) or, more common, was that the CCKW was typically not a last mile supply vehicle (thats what the jeeps were for) so it would have seen more 'improved' roads and there are PLENTY of wartime pics with 'street' tread tires.

But if you want 'the look' then its $220 a tire ($168 is a good deal.. probably at a show with no delivery charge).

the truck pictured belonged to a friend of mine. The 9.00 x 20 did rub a bit when off road. For the record we still have the 750 x 20s that came off the truck. They are in great shape but are snow tires. $300 for all 10

I think, that the braking problem is a smaller issue for the Jimmy brakes have a good potential if in propper shape. And many Armys did conversions on tire sizes and no brake problems are reported, at least in Europe.
Technically, the rear axles have a tendency to overbrake, but that is a feature of the time they were built. And there are to my knowledge no down size rear wheel cylinders available. The front brake is with propper adjustment and pressure supply a real good ones. However not with WWI NOS brake linings. These contain asbestos and are nowadays illegal in any part of the world. New linings are useually of better performance (better friction coeficient and less wear).
Wolf

The dump truck I parted out had 7.5 x20s on it.. NATO tread and made in England. Still has some of the french data plates.

Don't get me started on tires

i have 900x20s on my 42 no brake problems and front tire rub was solved using non dual wheel rims think they were from an m135.good luck

by the way the m35 duals will not work right on the rear you need cckw rims as was posted earlier or reweld the m35 centers to a different offset.

Most brake setups are plumed to understear the vehicle (make the front lock up first) that is an important safety issue. If you lock up the rears, they you can 'skid out' much easier.

I don't know if there even is a proportional valve in the CCKW or the M35 brake system... I doubt it though, both are single circuit.

I would rather go with 7.5x20s in a a street tread (very common in WWII) rather than NDTs. NDTs suck on wet or dry pavement. Next time you are out driving on NDTs look out the rear view side mirror at the rear tires. The *ONLY* part that is touching the road is that 2 inch center rib. The entire rest of the tire is just along for the ride.