Dudelux - They'll work better far, far below 16psi. When I ran Q78's on my Gwagen, I'd start at 12 and drop them as required from there. I ran as low as 5psi.
It's very dependent on wheat you are driving though. In straight out technical terrain, the trade off is between lateral stability, diff clearance and traction.
At higher speed it's handling, likelihood of rolling a bead, and heat build up.
Gearing, centre of gravity, and weight distribution all have a bearing too.
As for holding a bead, swampers can be very good, but 2nd hand tyres often have had some bead damage due to unseating and that can loosen them up. Rim design also has a lot to do with how well tyres hold on.
Personally, I'd try around 10 psi without beadlocks but so long as you have air on board loosing a bead offroad isn't a big deal, so you can experiment lower.
To get an idea of what's a desirable pressure air them down by eye. Do this with the tyres warm from a road drive. You might find you end up with more in the front than the rear due to weight distribution, and once you get a nice bag to the tyres, then check the pressure and use that as your guide. We did this once with a sierra with fresh Q78's on it (beadlocked) and came up at 2.5psi front and 1.5 PSI rear. My heavily used 78's bag well at around 5 psi on my (admittedly heavier) car.
IMHO though, any tyre intended for offroad use cannot work properly at the epssures required for it to stay on the bead - beadlocks are a necessity to get the most out of ANY tyre.
Alien - I wasn't implying that the LTB came in 32X9, only that if the coice had to be SSR or LTB, I'd go the LTB. Correct the 32X9.5 15 is a TSL bias tyre only. Radials are inferior for offroad work for the same reason they are superior for on road work - the tread is excessively stiff. I maintain the 32X9.5 would be superior to either the 31 LTB or SSR on a sierra.
I mostly recommend the 32X9.5 as the height to width ratio will give you improved drivability compared to a 10.5 and especially a 11.5. Personally, I'd go straight to a 34 9.5 15 to gain footprint length, but I appreciate you reasons for staying at 31-32". Having said that, swampers aren't road legal in post 1972 cars anyway so being on an engineered size is pretty irrelevant.
Here's a low SPOA car, no BL on 34X9.5 15's:
Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
) and are pretty tough.
