Tire width, steer linkage damage ?

two-bit

Precision Fit
Apr 11, 2016
713
West Ishpeming MI
First Name
Tony
Willys Model
  1. Pickup
Willys Year:
  1. 1960
Hello all, I am not usually in this forum because i am pick-up owner. However there is a question i have about early CJ steering linkage and wide tires. A local guy near me, who is 19 yrs old, is bound and determined to run 12.50 wide tires on his "jeep soup" 51 CJ 3. (Its a huge collection of parts he has been putting together since he was 14.)
I have always been led to believe that wide tires on the steer axle were always bad for the linkage (ie: rod ends, pitman arms, ect) because it causes to much stress via drag friction from the wider tires. It makes sense to me, the pick-ups are the same way narrow tire, less stress on linkage.
Did the CJ's have tougher steeing parts ? Can they handle wide tires better than i think they can ? Am i making a mountain out of a mole hill?
He will day drive it this summer, cause it will be road ready. I don't want to see him get into an accident because of steering failure. I may not be able to change his mind, but i would like to know if i am right or not.
He is running an old closed knuckle, drum brake, front diff. Damned if i know what its out of. Linkage is tight right now, don't know if it will last.
TIA.
 
Tony
I'd be happier to advise the youngster about his Jeep than I would someone else.
But.. in the spirit of his welfare, I will. He will learn that 12.5 tires will wobble that Jeep all over the road first. It will be close to unstoppable with those 9" brakes, and that steering box that was designed in the 1930's will be way over matched, especially to a teenage driver. Off road those tires will provide too much traction for a 60 hp. Jeep engine to spin around efficiently. I would tell your kids, and their friends to not ride with him and why. With a little luck he will soon figure out that his tires are a problem. Or his Jeep will be broken more than together.

To answer your other question, A Jeep CJ2A or any 4 cyl CJ will have then same front axle as a pickup, only narrower. It's mostly the brakes, short wheelbase and hard steering that will be problematic. It's not exactly weak front axle design (if it all is in good condition that is) that is the problem. And, if he is a "learning" mechanic there's a whole new problem.

FULL DISCLOSURE All on this forum were "learning" mechanics once, screwed things up, and learned from same. And we are still learning.

The "Jeep Soup" phenomena really is moot, as so many parts are interchangeable on so many early jeeps that everybody does that anyway. I sure did. A good question to ask will be: "Do you have the same ratios in the front axle as the rear?" He should know the answer.
I wish him luck!
diggerG
 
Thanks for info DiggerG. I will talk to him. See if i can convince him. The front and rear ratio's do match, i asked him that a while ago. As far as the "learning " part goes. I too am still learning after 30 years of wrenching, your statement is so very true.
 
There's also the issue of traction. A light CJ on wide tires actually has less effective traction on some surfaces because the lbs per square inch on the tire contact patch is less. If you increase the contact area of the tire and keep the weight the same, the per square inch load goes down.
If you need high flotation tires for soft ground then wider is better. Most other surfaces are better with narrower tires.
Do the math.
And, yes, the steering linkage will survive the wide tires for a while but you won't like the handling, especially on the road at speed. Can you spell dangerous?
 
Absolutely right on the traction issue John. i didn't quite explain it correctly.
diggerG
 
I have 30x9.5x15 on my (near) stock standard 3B (only front disk brakes and the addition of a stabiliser shock added). Have had these tyres on for about 3 years. I often run on the beach and in wet and muddy paddocks and generally drive around town. Traction is certainly better than with standard skinny's.
Maximum speed I run at is about 55mph but generally stick to a maximum of 50mph due to the gearing. There are no issues with loss of power that I can tell.
My steering has never been terrific but it is no worse for wear and drives fine on 9.5" tyres.
Mike
 
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A 9.5 tire is a heck of a lot skinnier that a 12.5 is and a heck of a lot more friction and drag in soft material.
diggerG
 
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