Tire pressure

[Clawed Backster]

I've got an old Michigan wheel dozer with 29.5-25 Michelin radial tires on it. A previous owner filled them with liquid. The tires seem to be very old, as the tread crumbles away pretty badly on rocky ground. The machine weights 63,000 pounds, and I would estimate that 70% of that weight is on the front axle. I don't know what pressure to run, and I feel that the biggest danger is excessive sidewall flex causing them to split due to their age.
BTW, this machine gets very little use, as it is just used around my property for little projects, so no, I won't be replacing them with newer tires.
Opinions?

 

[funwithfuel]

Sidewall flex is your suspension. What model loader do you have? We could try to find recommended pressure.

 

[Clawed Backster]

Sidewall flex is your suspension. What model loader do you have? We could try to find recommended pressure.

It isn't a loader, but a wheel dozer. An old Michigan 280, straight frame unit. I read somewhere that a loader with that size tire would run 85psi in the front, and 60 in the rear, but that is with new tires, not ones that are probably 50 years old.

 

[ianjoub]

Is the max pressure not molded into the sidewall of the tire?

 

[Clawed Backster]

Is the max pressure not molded into the sidewall of the tire?

No, not that I have been able to find.

 

[Nige]

I read somewhere that a loader with that size tire would run 85psi in the front, and 60 in the rear

For a start it all depends on what type of tyre you have installed and for Michelin radials what * rating they are.
The sidewalls should be marked with the tyre type (XLD, XHA, etc) followed by either L-3, L-4, or L-5, and could be marked anything from * to ***.

A wheel dozer will generally run much lower pressures than a loader, especially on the front because it does not have to lift a bucket load of dirt. For comparison a Cat wheel loader of a similar physical size to your Michigan running 29.5R25 tyres the recommended starting point for pressures would be 50psi front, 30psi rear.

 

[Clawed Backster]

For a start it all depends on what type of tyre you have installed and for Michelin radials what * rating they are.
The sidewalls should be marked with the tyre type (XLD, XHA, etc) followed by either L-3, L-4, or L-5, and could be marked anything from * to ***.

A wheel dozer will generally run much lower pressures than a loader, especially on the front because it does not have to lift a bucket load of dirt. For comparison a Cat wheel loader of a similar physical size to your Michigan running 29.5R25 tyres the recommended starting point for pressures would be 50psi front, 30psi rear.

Thanks for the info. It just seems to me that that my tires squat and the sidewalls flex quite a bit, and like I said, I am concerned that considering their age, that they may crack/split. The rubber of the tread does not seem very flexible, and chunks off on rocky ground.
I had to order an adapter for the oversized valve stems, because I can't find the one I had, but I checked them in the past, and if I remember correctly, they were about 30psi.

 

[funwithfuel]

Down towards the bottom, where it shows performance data chart, it calls out the tires being at 30 as Nige suggested. It also shows them being liquid filled like farm equipment. You want to make dure your valve stem is at 12:00 , that crap will corrode the guts out of an inflator-gauge.

 

[crane operator]

I don't think increasing or decreasing the pressure a lot is going to help your tires survive. They are a pressure vessel, just like a air tank. And yours are obviously coming apart from what you've said.

The fluid is to increase weight to get traction pushing. Lower pressure is going to give you more traction across the tire also. Just enough air to keep them on the rims, so I think anywhere from 30-50 psi would be fine.

I realize new tires are out of the question, but I'm going to suggest you try to find a used set coming off of a quarry loader, something a lot newer, even if they don't have much tread left. You don't use it a lot so you aren't likely to wear them out. But you don't want to have one blow out. Find out who does industrial tires in your area, let him know what you are looking for, and I know they will come up with a set.

I had a 23.5r25 blow a few years ago on a 70,000lbs crane. It was about 5pm, after we had left for the day. Customer was 1/2 mile away, and said it was like a bomb going off- it blew chunks out of the pavement. I was just glad no one was standing by the crane when it went. The tires were older on my crane, and I'd been replacing them and this was the last old one on the crane.

If one blows with anyone nearby, it will ruin your whole day. Find some better rubber.

 

[Nige]

It just seems to me that that my tires squat and the sidewalls flex quite a bit,

The nature of the beast where Michelin earthmover radials are concerned AFAIK.

With a 75k pound wheel dozer I wouldn’t suggest ballasting the tyres unless frequent loss of traction is a problem. The tractor is already heavy enough.

 

[Clawed Backster]

I don't think increasing or decreasing the pressure a lot is going to help your tires survive. They are a pressure vessel, just like a air tank. And yours are obviously coming apart from what you've said.

The fluid is to increase weight to get traction pushing. Lower pressure is going to give you more traction across the tire also. Just enough air to keep them on the rims, so I think anywhere from 30-50 psi would be fine.

I realize new tires are out of the question, but I'm going to suggest you try to find a used set coming off of a quarry loader, something a lot newer, even if they don't have much tread left. You don't use it a lot so you aren't likely to wear them out. But you don't want to have one blow out. Find out who does industrial tires in your area, let him know what you are looking for, and I know they will come up with a set.

I had a 23.5r25 blow a few years ago on a 70,000lbs crane. It was about 5pm, after we had left for the day. Customer was 1/2 mile away, and said it was like a bomb going off- it blew chunks out of the pavement. I was just glad no one was standing by the crane when it went. The tires were older on my crane, and I'd been replacing them and this was the last old one on the crane.

If one blows with anyone nearby, it will ruin your whole day. Find some better rubber.

That would probably be the ideal solution if it weren't for the fact that I have been married for 34 years, and would really like to stay that way. Lol
The little woman wasn't very happy that I spent $108 yesterday on a new air line for the dozer, as she considers it to be my toy. Yeah, even used tires are out of the question, so I am just looking to take the best care of the ones I have.
And I am very familiar with what an exploding tire is like. They are no joke.

 

[crane operator]

If you can't afford the tires, you can't afford the dozer. Its just part of the cost of ownership.

 

[Welder Dave]

A blow out could be catastrophic. I see new and used tires at the RB sales all the time. I've seen dealers list them too starting at a few hundred bucks.