Would these tires work?

[beck-529]

Sorry if this has been answered before. I’m kind of new at the big trucks.

I want to make a C50 into a 70 mph truck. That doesn’t work well with the stock tires. Would 275/65R20 tires work on these trucks? If so I expect a tube would be needed in them?

http://www.tirerack.com/tires/tires....160508150658:s

These tires are 34” in diameter compared to the over 40” stock tires. I would install an overdrive transmission. Gearing would still be a problem. What was the fastest gear ratio available and how rare was it?

My truck would be used to pull an enclosed trailer. It wouldn’t have much of a weight load. I am looking at lowering the truck so the tires wouldn’t look too tiny in the front wheel opening.

[BlueDiver]

I hope someone can answer this one.... I'm working on a C50 as well and am wondering how to make my truck interstate ready as well....

Good to hear from another C50 guy. Not too many of us.

[jumpsoffrock]

If your tires are 20" tires marked on the side and you don't have dayton hubs, that means you have 2 or 3 piece rims, possibly widowmakers(Firestone RH-5º) or Budds.
These wheels are nothing like what we have today. Those tires you have listed are made for modern wheels found on small trucks and cars...completely different world.

To turn it into a 70mph truck will be a tall and very complicated order. Need much taller gears and tires. With respect to medium and heavy duty trucks, all tires of a whole denomination are tube tires, and all decimal denominations (19.5", 22.5") are tubeless tires. To use tubeless tires, you must have modern tubeless wheels.

Finding tubeless wheels that fit our hubs(I have a '67 C50 and went through everything you are asking about) is extremely hard. They are all based off of Accuride 28160 wheels, discontinued for a few years now--very hard to find.
They make repro Accurides today, and they are not cheap, and very heavy, not too good looking.


This is a very common subject and problem, so do some searching. There is no cheap/easy fix to your problem, so long you have conventional hubs and not Daytons.


Dayton hubs:


Conventional hubs:

[beck-529]

Thanks jumpsoffrock,

Your answer is kind of what I was expecting, but not what I wanted to hear. The Dayton wheels are not very attractive to me. I have passed on a couple of trucks just because they had dayton wheels.

If I cannot make the truck drive interstate speeds it just won't work for what I need it to do. I sure do like the way they look. Cool trucks.

The only solution I have seen so far is the blank wheels on Ebay. Buying and machining these wheels and new tires would be over $3500. That puts them out of the budget.

[mrolds88]

Beck, I would start with a tape measure and a trip to a local medium duty/ big truck yard. Take measurements of your truck rear with you and compare. As far as those tires are concerned, they are wrong for what you are trying to accomplish in 2 ways. First is weight rating. While they have D&E rated tires and would hold the truck up, They aren't rated for the moving weight of the truck. I had a 70 C50 that weighed in at 9600 with a dump bed. And second, you would be going in the wrong direction size wise. A 34 inch tire will have to turn more times to go the same distance as a 40 inch tires. Since you cant go much taller on the tires, you should look into the overdrive trans and a later rear axle with a more speed friendly set of gears. As far as the overdrive, one resource that you may be able to exploit is old army deuce and a halfs. The trans will bolt up to a Chevy bellhousing. Do your research, it will pay off.

[JPBrecheisen]

Originally Posted by beck-529

Sorry if this has been answered before. I’m kind of new at the big trucks.

I want to make a C50 into a 70 mph truck. That doesn’t work well with the stock tires. Would 275/65R20 tires work on these trucks? If so I expect a tube would be needed in them?

http://www.tirerack.com/tires/tires....160508150658:s

These tires are 34” in diameter compared to the over 40” stock tires. I would install an overdrive transmission. Gearing would still be a problem. What was the fastest gear ratio available and how rare was it?

My truck would be used to pull an enclosed trailer. It wouldn’t have much of a weight load. I am looking at lowering the truck so the tires wouldn’t look too tiny in the front wheel opening.

You could always find a modern roll-back type wrecker truck possibly and just put the old body on it.

I understand wanting the higher speeds, but keep in mind you still have to steer and stop from those speeds also.

Like jumpsoffrock noted, wheels for the old GM medium duty trucks are near impossible to find unless you have a lot of patience and perseverance. I looked for years, and only found 2 of them in the 22.5 tubeless version. I ended up with the aftermarket ones and they are heavy and kinda ugly.

You run out of "mod" options on these trucks pretty quickly if you're trying to use original GM stuff.

If you want a highway speed type deal you might be better off putting all new running gear in from another late-model outfit.

Good luck with your project.