In a pinch

[CID]

The only thing that matters is the rolling radius as that x two is effectively the new diameter as far as the machine sees it.

Not true, the larger circumference tires will turn fewer revolutions for any given distance causing the driveline to bind up any time 4wd is engaged.

 

[ODAMO]

Not true, the larger circumference tires will turn fewer revolutions for any given distance causing the driveline to bind up any time 4wd is engaged.

Lowering the pressure in a tire puts the axle centerline closer to the ground and the rollout of the tire will be reduced. A 40" tire deflated so that the axle is 15" off the ground instead of 20" will travel the same distance as a 30" tire because both rolling radii are equal.

 

[CID]

Lowering the pressure in a tire puts the axle centerline closer to the ground and the rollout of the tire will be reduced. A 40" tire deflated so that the axle is 15" off the ground instead of 20" will travel the same distance as a 30" tire because both rolling radii are equal.

Try that on hard pack or slickrock and get back to us.

 

[Scoop]

Whatever R U thinkin'? Tires - all four are either 30 x 9.5 x 15 or 30 x 10 x 15 depending on mfr. Front rims 6+1, rear 4+3.

Dood ... I was messing with you, cause 9.5 <> 10

 

[CID]

Dood ... I was messing with you, cause 9.5 <> 10

I know, saw the smilie but elaborated for those following along. Further elaboration - I'm either running four 9.5s or four 10s, all four corners get the same tire.

 

[ODAMO]

On a 4x4 tractor with bigger size tires on the rear the difference in rolling radius is made up for in gear ratio. The same sffect can be had with "adjusting gear ratio" with lowering tire pressure hence rolling radius.
Not optimal but "in a pinch" it works. We are not talking about tire wear, just rolling radius.

 

[CID]

The distance a tire rolls per revolution is determined by its circumference, not its rolling radius. Yes, in a pinch, you can get back to the trailer but I wouldn't intend to ride it that way for a weekend and you'd best not put it in 4wd, either locked or i4wd.

 

[ODAMO]

I know you think I'm makin this up but if you drive your truck down the highway and use your gps to gage your speed and compare to your speedometer, And then do the same with 5-10 psi less you will see what Im saying is indeed correct. Your gps compared to the speedometer will show the difference and that relates to tire revolutions per mile.
OR we can just wait for Kyle to do it and report back that he did not f*** up his machine.

 

[CID]

I know you think I'm makin this up but if you drive your truck down the highway and use your gps to gage your speed and compare to your speedometer, And then do the same with 5-10 psi less you will see what Im saying is indeed correct. Your gps compared to the speedometer will show the difference and that relates to tire revolutions per mile.
OR we can just wait for Kyle to do it and report back that he did not f*** up his machine.

An engineer just did a test to check this out. Dropping tire pressure from 50 down to 10, showed .9% difference in rolling distance, a nearly insignificant change in rolling distance because the tire's circumference remains the same, like I said.

 

[ODAMO]

I agree that with a radial tire there will be little difference, but there is still a difference. We were talking about bias ply tires, especially the ones that come on the Pioneer. If the same test is done with bias ply tires the differences will be much greater. Especially if one is over inflated and the other is underinflated because they can stretch much more than a steel belted radial. I would guess the measurable difference would be more on the order of atleast 10 percent. Ask a drag racer that uses a spool and bias ply race slicks if equal air pressure side to side is important.