i put air in when the rim touches the ground.

so i should be ok to run mine at 10psi b4 i start popping beads????

so i should be ok to run mine at 10psi b4 i start popping beads????

Depends on tyre and wheel type, the amount of time the tyres have been on the rims, driving style, and terrain.

Generally, 10 psi should be no problem - look at the number of people who have responded to your post with 10psi as their preferred pressure.

I am suspicious as to how many people have aired down until the tyres fell off and then worked up from that point though - I've seen people running 5psi on unbeadlocked rims without a problem, under certain circumstances. With radials in good condition that have been on rims for a while, I would have thought 8psi would be fine too.

You can always experiment with sikaflex or mastic to prevent the tyre falling off. I haven't found this to be very effective though. RTV Silicone is NOT effective in holding tyres on beads.

There's also two different constructions that are relevant here. Radials have a very stiff tread and soft sidewalls. The minimum pressure in a radial is determined by when the rims will touch the ground. Radial tyres work better the lower you go up until the point the rim starts to hit the ground. The compromise is that when on side angles, the tyre won't have enough lateral stability and will tuck under the car and make the car less stable.

Cross ply tyres (Simex, swamper, Comp Trep/Creepy, many 7.50 16 "mine service" tyre tyres) has a flexible tread and a stiff(er) sidewall. Crossply tyres are a bit of a different thing. The tread will start to fold up (crease down the middle) at higher pressure than a radial will normally show problems at. Still, air a cross ply down by eye rather than gauge and you'll be surprised how low you go before they start to bag.

The key is to find tyres with low load ratings. You never want anything with a load rating over 'C' or 6 ply on a sierra if you can avoid it. Higher load ratings mean you'll have to go lower with air pressure to get the tyre to perform and that means it's more likely to fall off the bead.

Steve.

Depends on tyre and wheel type, the amount of time the tyres have been on the rims, driving style, and terrain.

Generally, 10 psi should be no problem - look at the number of people who have responded to your post with 10psi as their preferred pressure.

I am suspicious as to how many people have aired down until the tyres fell off and then worked up from that point though - I've seen people running 5psi on unbeadlocked rims without a problem, under certain circumstances. With radials in good condition that have been on rims for a while, I would have thought 8psi would be fine too.

You can always experiment with sikaflex or mastic to prevent the tyre falling off. I haven't found this to be very effective though. RTV Silicone is NOT effective in holding tyres on beads.

There's also two different constructions that are relevant here. Radials have a very stiff tread and soft sidewalls. The minimum pressure in a radial is determined by when the rims will touch the ground. Radial tyres work better the lower you go up until the point the rim starts to hit the ground. The compromise is that when on side angles, the tyre won't have enough lateral stability and will tuck under the car and make the car less stable.

Cross ply tyres (Simex, swamper, Comp Trep/Creepy, many 7.50 16 "mine service" tyre tyres) has a flexible tread and a stiff(er) sidewall. Crossply tyres are a bit of a different thing. The tread will start to fold up (crease down the middle) at higher pressure than a radial will normally show problems at. Still, air a cross ply down by eye rather than gauge and you'll be surprised how low you go before they start to bag.

The key is to find tyres with low load ratings. You never want anything with a load rating over 'C' or 6 ply on a sierra if you can avoid it. Higher load ratings mean you'll have to go lower with air pressure to get the tyre to perform and that means it's more likely to fall off the bead.

Steve.