I suppose it likely makes a difference whether the particular 19.5" tire in question is F, G or H load rated. I would have to imagine that an F load rated tire would deform more with reduced pressure than an H rated tire at the same reduced pressure, both carrying the same loaded weight.
That's a good point. We have "H" rated 19.5" tires that have really stiff sidewalls and the tires are rather narrow to boot. I also think that all 19.5" tires do not have a bead which is a factor that curtails effective airing down.
I think if there was a way to utilize this tire for beach use here at Assateague Island, Rickson Trucks would have announced it. This is a pretty big market for TC's going on the beach. Dan, at Rickson, which is located North of Baltimore, says flatly 19.5" tires can not be safely used airing dowm. Sidewall damage when the tire comes off the wheel along with too much flexing of the steel sidewalls are the concerns. My tires also have a small footprint, they don't mushroom properly.
2004 F350 Diesel CC SRW 19.5" Rickson W/T 4WD
2005 Lance 1121 well found.
12' Porta-Bote alongside
All that glisters is not gold. All who wander are not lost. See us on YouTube" Living the Lance Life" 3 of 4.
Opportunity - someone needs to manufacture slip-on boots for 19.5" tires for beach riding. Typical speeds would be low on the beach and I think all that would be needed would be a wider footprint to spread the weight.
I have a F450 also with 19.5 rims, I air down to 25 PSI with no problems.
It dose make a big differance to air down with 19.5 tires.
Take this advice with great caution. The vast majority of people here and as far as I have seen ALL of the tire manufacturers disagree with this "practice".
I would NEVER try to air my 19.5's down to 25PSI unless the specific tire manufacturer in question said it was OK, and if one DID say that, they would probably attach a speed rating for it. Michellin says the minimum tire pressure allowed for my tires is 80PSI if I recall right (it is within 5PSI of that I think.)
I am not willing to risk damaging any of my tires that are $350-400 apiece (by the time you figure in mounting etc.)
Sometimes you may have to do something not recommended, sure. I've ridden both of my dirt bikes for 30+ miles including on hard-core 4x4 trails (such as Pritchett Canyon in Moab) with a dead-flat rear or front tire. Is it recommended? No. Did it damage my wheels, yes at least once. But was there any other (good) choice, no. So I'm not a "you have to stick to the rules" guy, but in this case, I wouldn't do it unless it was an emergency, and even then I would expect consequences.
* This post was
edited 08/18/11 12:30pm by btggraphix *