How many pounds air pressure in firestone rears on my 641?

[whitedogone]

I just removed the fluid, repaired the damage around the valve stem, and installed a new tube from one of my rims on the 641.It has 14.9x28 Firestones on it. What psi do I need to run them at?

 

[jinman]

I like to run 20-25 psi because that will keep the rears from slipping on the rims and possibly damaging the tube. If you get in a situation where you need slightly more traction, you can always let air out. I think 25 psi in the rears keeps them wearing nicely and holds the cleat geometry so you get good traction.

 

[DieselMonk]

I run about 12 to 15 psi.

 

[RickB]

Enough to have the tread bars in full ground contact and a little bulge in the sidewall. Correct PSI will vary with the load the rear axle is carrying. You will probably end up in the 12-15PSI range. 20-25 will be too hard unless you have a mounted backhoe or similar rear ballast. Too much pressure = less traction, more soil compaction, harsh ride, accellerated tire wear in the middle of the tread. Too little pressure= sidewall damage, possible tire slip on rim bead, loss of traction as tread rolls up in the center under load.

 

[jinman]

I hate it when I say something and have to take it back.:ashamed: RickB and DieselMonk are right and I'm wrong. I quoted pressures off the top of my head and ended up suggesting something that applies to loaded R4s with heavy weight, not ag tires. To make sure I was wrong, I finally opened my old Ford 1954 - 1964 Manual and found the suggested inflation pressure for 14.9-28 4-ply rear tires is 14 psi, and the suggested maximum weight load is 2630 lb per tire. So, it would seem I blew it in spectacular fashion.

 

[Bob77064]

My tractor has R4s that are not loaded, I keep the fronts at 35 and the rears at 14. The higher pressure in front is because I use the FEL. With 760 pounds on the TPH the rear tires do not flex.

 

[sparc]

Are there any tractor tire/wheel combinations that use a beadlock as is done with some offroad tires on 4x4 trucks or like on a HUMVEE or like on my Hummer H1?

On my H1 I had the optional CTIS (Central Tire Inflation System). With it you can use the onboard compressor to air up or down as conditions required. You can be driving down the road at 55 MPH and direct air pressure to the front or rear axle or both using a selector valve in the cab. A duplex gauge on the dash gives the pressure in each axle. The air is fed through a hollow spindle out to the tire.

 

[DieselMonk]

I hate it when I say something and have to take it back.:ashamed: RickB and DieselMonk are right and I'm wrong. I quoted pressures off the top of my head and ended up suggesting something that applies to loaded R4s with heavy weight, not ag tires. To make sure I was wrong, I finally opened my old Ford 1954 - 1964 Manual and found the suggested inflation pressure for 14.9-28 4-ply rear tires is 14 psi, and the suggested maximum weight load is 2630 lb per tire. So, it would seem I blew it in spectacular fashion.

I am just glad things like that don't only happen to me alone! Got proved otherwise before as well...