BX25: Fill rear tires or not?

94BULLITT · Dec 10, 2012

EE_Bota said:
I have offered this theory before, and nobody saluted. I will offer it again, but I don't expect any salutes this time either.

Air is compressible and fluids essentially are not. If you hit a bump of the proper shape under the right circumstances, perhaps that could be problematic if the tire is filled. Problematic to what? The tire, the axle, the bearings, who really knows. Fill the tires, put on the backhoe, and hit the right speed bump at the right speed, and send in the video and we will all have our opinion I reckon.

When I was looking at possible backhoe additions to my BX2200, the backhoes were well beyond what the lift could handle, which is ONE of the reasons they were sub-frame mounted.

My BX2200 has no backhoe, I decided to buy an additional tractor. But my BX would be nothing without filled tires. Were it me, I would fill the tires, but I would be a truly slow mover with the backhoe on.

The tires are not filled all the way so there is a cushion. They get filled to 75%.

EE_Bota · Dec 11, 2012

94BULLITT said:
The tires are not filled all the way so there is a cushion. They get filled to 75%.

I know, I think someone pointed that out last time too. But if I had to fall backwards onto an air mattress 100% full of air vs one 25% air 75% water, I'm concerned I may detect a difference. And the sides of a tire are far less likely to bulge outward in a manner that could be described as stretching since tires don't really stretch much. They deform to a different shape, but there are cords and belts everywhere to try to avoid substantial stretching.

Another example...imagine an hydraulic cylinder full of air vs one with 75% fluid 25% air. Now after thinking about that a bit, do the same for a bladder commonly used in air suspensions. We see them on transfer trucks all the time. If we fill that bladder 75 % full of water and only 25% air vs the normal condition of all air, what does that do to our air ride suspension?

I may certainly be wrong, and maybe that's why no one is saluting. But I truly believe that physics is on my side.

I could try the gas law PV=nRT, but there will be 2 cases and 4 states, and I don't know what numbers to plug in. I typically only go to that amount of work when I need actual magnitudes for my answer, not when a thought experiment will be sufficient.

JOHNTHOMAS · Dec 11, 2012

EE-BOTA.....I salute you!:thumbsup: :cool2: :thumbsup: .....

EE_Bota · Dec 11, 2012

JOHNTHOMAS said:
EE-BOTA.....I salute you!:thumbsup: :cool2: :thumbsup: .....

Hey! Thank-you JOHNTHOMAS. I wouldn't even care if it were a pity salute at this point.

I'll just take it and smile.

radioman · Dec 11, 2012

gee ee bota --- you are making my head spin! No not really- I think I comprehend what you are saying and it got some merit. for some reason the waterbed analogy is sticking in my head and I am thinking that if I plopped into the water bed compared to an air mattress - you have a point there. The only hole in your theory is that the BX has a top speed of 8 mph at WOT in rabbit. 8 mph? a bump in a semi fluid like tire? I gotta mull on that one a bit and think if there "might" bee any damage, but I hardly can fathom one.

EE_Bota · Dec 11, 2012

radioman said:
gee ee bota --- you are making my head spin! No not really- I think I comprehend what you are saying and it got some merit. for some reason the waterbed analogy is sticking in my head and I am thinking that if I plopped into the water bed compared to an air mattress - you have a point there. The only hole in your theory is that the BX has a top speed of 8 mph at WOT in rabbit. 8 mph? a bump in a semi fluid like tire? I gotta mull on that one a bit and think if there "might" bee any damage, but I hardly can fathom one.

Yeah, I see what your are saying. I first came up with the theory when I saw the first debate on here about filling front tires. There is no way that is enough weight to matter. I was using my FEL, and doing just fine, and I hit a rock with one of the front tires and the tire sort of collapsed and absorbed that without making my filled FEL move upward in proportion to the insult (even considering the axle pivot.) I thought it would make a much harder tire were it filled, and something might have to give, and if I were lucky, it would be the tire itself.