G506 tires

[MChapin]

Taking the Chevy on a long trip. Tires are fine for local parades, but need to be replaced for the trip. I have been giving this some thought and would like your input. Of three tires, the Denman is the smallest Diameter, STA is next, with a very old Firestone being the largest diameter( this may be from the 40's). There is quite a gap between the Denman and the Firestone, which I feel changes the final gearing, affecting rpm's etc. The current 8.25-20 is closer to the old Firestone in diameter. Is anyone running this tire? Any issues?

Thanks.

[m5a1stuart]

Isn't all the 7.50x20's the same diam.?

[MChapin]

Actually, there not. The Diameter is different between Manufactures and even different between individual tires. Some differences are driven by cost. I believe these smaller diameter tires are hurting the performance of our older trucks. If you use the vehicle for parades only, it won't make much difference. But if you are going to put some miles on it, it will make a big difference. In my racing days we used a spec tire that was made overseas. There would be as much as 2 inch difference between tires. Knowing this made a big difference on the track. They moved the tire building back to the USA and now they are very close.

[Ben Dover]

For some reason Denman chose to use a 7.50X20 NDT Mold that is the better part of 2" smaller in diameter than US Royal, Uni Royal, and the diameter of STA.
Military Tread (NDCC and NDT do differ in diameter with commercial tread counterparts. The STA is the only brand 7.50X20 NDT that is in production in the USA. The other made in USA brand 7.50X20 NDT mentioned such as US ROYAL, Uni Royal are long out of production and a chance encounter.

If I were going to use my G-506 Truck on long over the highway trips, Commercial Tread 7.50X20 tires would be the choice, they are quieter and wear better.
Post War Chevrolet 4X4 and CCKW trucks with civilian tread were a common sight on military bases.

[MChapin]

Thanks Ben. So far the commercial tread tires I have looked at are smaller in diameter than the ND. But I am inclined to go that way. Most of the driving will be on paved roads in the wet season. (Alcan highway next August).
As a note- the Denman is almost 3 inches smaller in diameter than the old Firestone.

[Ben Dover]

And there are longtime Denman 7.50 X 20 NDT users thst have recently received STA 7.50 X 20 NDT tires that could not believe the Tire Size printed on the STA and were convinced that STA had used 8.25 X 20 NDT molds. Denman 750 X 20's have been shorting the users for years. STA 7.50 X 20's have been consistant with other brand 7.50 X 20 NDT tires and use a genuine mold for Gov't issue tires.

[TopKick]

What about the tires made by Wallace Wade?

[Ben Dover]

Wallace Wade sells the same tires as the rest of the dealers, STA is the only one producing the 7.50 X 20 NDT at present.

[Zack Magnusson]

I'm interested in this discussion in that I would like to put correct 750-20 NDT tires on my G506. I am currently running 900-20 NDCC's that came off an M-35 which measure about 39.5" tall. My redneck buddies can't understand why I'd want to go smaller! When I look at the price of seven 750-20 NDT tires, tubes, flaps, etc, I start to question it too.

Universal Tire: https://www.universaltire.com/truck-and-military/military/750-20-firestone-military-ndt.html
Firestone, 36.9" Dia. - $249 EA

Coker: http://store.cokertire.com/popular-tire-applications/vintage-military-tires/750-20-firestone-military-ndt.html
Firestone, 36.9" DIA - $249 EA

Specialy Tires of America: http://www.stausaonline.com/military/ndt.html (Wallace Wade sells these)
STA, 38.5" DIA - $? EA

I just measured an old Mansfield 750-20 NDT that came off a Water buffalo at about 35" tall. Not sure how old it is, but it is quite dry and cracked and has pretty good tread left on it.

Here's a photo of the 750-20 NDT leaned against a 900-20 NDCC on the truck:

[Ben Dover]

Let's face it, tires are expensive. The G-506 and G-508 have 7" wide wheels and smaller 7.50X20, the there is a glut of 9.00X20 M-Series tires mounted on 9" wide wheels, they are a lot larger and do not match the WWII trucks but the price is right.
The difference can be detected when driving the G-506 and G-508 .

[MChapin]

Zack- How do the 9:00x20's fit? The 8:25x20 seems to be closer to the old Firestone I have in diameter. Though it is a much heavier tire than needed. I will be putting close to 5000 miles on the truck this summer. Have to decide if the lower RPM's are worth the extra cost.

[Zack Magnusson]

They fit fine. I just drove the old truck 20 miles to work this morning and do so about once a month. The only issue is that if you turn sharply right, the LF tire rubbs the leaf spring. You can buy the things, mounted on a wheel, in darn good shape for $50 each.

You can see photos of my truck with the big M-35 tires on it here: http://www.g503.com/forums/viewtopic.php?f=25&t=189499.

[lkyfwd]

Zack, How is the spare tire carrier working out?

[Ben Dover]

The 9-00 X 20 Tire may not fit the spare tire position on the 4X4 Chev and LWB CCKW.

[Zack Magnusson]

The carrier is painted, bolted on, and looks great. I'll eventually replace the bolts with rivets. I have not put a tire on it yet though. Here's a photo.



Joel is probably right. I bet the 900-20 won't fit.