Tire pressure for a bobtailer

[skydawg]

What would be a good tire pressure for a short wheelbase B61,bobtail only,275R/22.5 tubeless tires? Thanks.

[Swishy]

Drive around with the maximum pressure recommended for the tyre to allow the tyre to seat correctly on the rim

then let m down to  40 psi + or - 20

Should be like a ride with air suspension

U din say single or tandem (4 or 8 tyres)

cya

 

[skydawg]

Swishy,it`s a single axle....didn`t realize you could run them that low .Thanks.

[HarryS]

Mine's a S/A B 61 with bias ply and I run 45# and still get a rough ride. I'm wondering how much better a tubeless radial would be.

[Freightrain]

I still run about 70# in mine all around.  The fronts just squat a touch from engine weight.  

 

You won't gain much ride quality until you get some frame length.  That 5ft I put on mine made a World of difference.  When it was 150", it was just too short and bucked over every crack in the road.

[phildirt]

If you think that old truck is going to ride like your $75,000 pickup by airing down the tires, you are going to be disappointed.

The idea of running tires designed for 100 psi at 45 psi under a 12,000 - 14,000 pound truck is about as stupid as you can get,

[Mean Green]

I ran 50 psi in my b model as a single axle the tires were so hard and dry rotted it made no diffrence and short wheel base makes it worse I made mine longer and added tandum air ride wayyyyy better

[doubleclutchinweasel]

I ran my fronts at the recommended pressure, which was around 100 psi. The rears on an unladen tractor just need enough air to make them stand up.  45-50 is probably good. But, do seat them first like Swishy said. 
Required air pressure depends on the weight they will see. Less weight needs less air.  
True, it’ll never ride great. But I got mine quite good by dropping the air pressure and getting the rims good and true on the spokes. 

[Licensed to kill]

IMO, tire "pressure" is just a convenient way of adjusting the tire for proper squat. With tractor tires, they are specifically aired to a specific squat and only show a MAXIMUM pressure not to exceed. I will be setting my pressures the where the tire LOOKS right and whatever that pressure is, that is where I will run them (I suspect that to be in the 40PSI range but don't know yet). The comments about wheel base is just a fact of life. Short wheel bases will never ride as good as a long one, EVER and a single will never ride as good as a tandem (all other things being equal). In my Model A truck with coil overs in the rear, it was brutal riding with the standard 32PSI in the rear tires. I lowered the pressure for the proper squat (around 18PSI IIRC) and it rides better but with the short wheel base it will always be a lumber wagon for ride. My "B", with it's 156" wheel base will buck but with the b"proper" air pressure in the tires and not much air in the bags it shouldn't be TOO bad. Planing air ride on the steer axle as well. 

[doubleclutchinweasel]

You are pretty well right on the squat.  The best alignment guy I ever knew even recommended setting tire pressure that way.  He said to set the fronts at the max pressure listed on the tire, and adjust the rears so they would squat about the same as the fronts.  I have found this to be right more often than wrong.

On my 3500 Ram/Cummins, I run 80 PSI in the front and about 45 in the rear.  Does wonders for the empty ride.  The rears get bumped up to give the right squat when it's loaded.

[mechohaulic]

the pressure really depends on the usage; a single/ bobtail == why.is it to drive to the grocery store , truck show?  every statement above is totally correct; but it all comes down to the individual purpose. tire says 80= try it ,,it will be too rough a ride .adjust with trial and error.  yrs back I picked up a UPS style F-model non sleeper single axle from albany mack brought it to waterbury ct. wish some one talked tire pressure to me then !!  it was like riding in the flintstone mobile . had I been old like now I'm sure my teeth would have fallen out.