New tire options after sidewall puncture on Trailhunter.

[fur_runner]

This is immensely helpful. I'm embarking on a long trip with a lot of rough gravel and dirt roads and my question would be if it's even feasible (or safe) to consider airing down 5psi (from spec 33psi)to make for a more comfortable ride with these OEM Open Country tires.

I'm having to extrapolate here a bit, but it seems at 33psi were looking at each tire capable of holding ~2270 pounds and when airing down to 28 for a gravel road that drops to ~1900 pounds per tire. 1900x4 =7,600. Assuming a fully loaded Trailhunter (GVWR is ~6500 pounds) were still within ~1100 pounds but the margins are clearly at a limit.

Am I thinking about this right? It seems unwise to go any lower than 28psi with these OEM tires but at this point I'm looking for some extra guidance given I can't find any concrete PSI charts with these OEM tires. What say you experts? ...I rather wear out these tires before replacing them myself.

The OE Toyo Open Country AT IIIs are rated 116T, which means 2756lbs @ 44psi and 118mph sustained speed. Using the ETRO published data here for load ranges at inflation, and their general guidance of 10% of max safe speed reduction per 10% pressure reduction, it would look like this:

	24	25	26	27	28	29	30	31	32	33	34	44
Load	1982	2028	2116	2178	2216	2304	2392	2433	2491	2579	2619	2756
Speed	64	67	70	72	75	78	81	83	86	89	91	118

OE manufacturers set the tire pressure based on the needed load capacity + 10% safety margins, so you COULD read the table and say you could drop to 29psi and merely be at the needed load capacity. You just need to know to slow down if you're gonna air down

Could you air down to 28psi for comfort on gravel and rough roads? Yeah of course. Will it be a bulletproof setup with no risk? Ehhhhhhhhhhhh. Toyota picked 33psi for a reason. If it were me, I wouldn't go lower than 30psi on the p-metric tires, and I would ready to change a tire if need be

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[rule5]

The OE Toyo Open Country AT IIIs are rated 116T, which means 2756lbs @ 44psi and 118mph sustained speed. Using the ETRO published data here for load ranges at inflation, and their general guidance of 10% of max safe speed reduction per 10% pressure reduction, it would look like this:

	24	25	26	27	28	29	30	31	32	33	34	44
Load	1982	2028	2116	2178	2216	2304	2392	2433	2491	2579	2619	2756
Speed	64	67	70	72	75	78	81	83	86	89	91	118

OE manufacturers set the tire pressure based on the needed load capacity + 10% safety margins, so you COULD read the table and say you could drop to 29psi and merely be at the needed load capacity. You just need to know to slow down if you're gonna air down

Could you air down to 28psi for comfort on gravel and rough roads? Yeah of course. Will it be a bulletproof setup with no risk? Ehhhhhhhhhhhh. Toyota picked 33psi for a reason. If it were me, I wouldn't go lower than 30psi on the p-metric tires, and I would ready to change a tire if need be

Thank you for this. Great lessons all around. Much appreciated.

 

[rule5]

Welp. I'm sure glad I didn't air down. After about 70 miles in the North Dakota Badlands I punctured the tread and got a flat. A very non-technical road that a Subaru would easily eat up. A puncture repair kit saved the day and I was on my way. ...but I'm certainly considering swapping to new tires now given how much I'm off road.

Question - if I went with beefier tires which allow for airing down (due to sidewall reinforcement) does that mean the tread is also further reinforced? I guess I'm curious if I would have gotten a puncture on the tread even if I upgraded my tires.

 

[fur_runner]

Welp. I'm sure glad I didn't air down. After about 70 miles in the North Dakota Badlands I punctured the tread and got a flat. A very non-technical road that a Subaru would easily eat up. A puncture repair kit saved the day and I was on my way. ...but I'm certainly considering swapping to new tires now given how much I'm off road.

Question - if I went with beefier tires which allow for airing down (due to sidewall reinforcement) does that mean the tread is also further reinforced? I guess I'm curious if I would have gotten a puncture on the tread even if I upgraded my tires.

Probably not. All tires already steel belts supporting the tread, so some extra rubber isn't gonna make a big difference. Is something like OC3 gonna have *more* belts or reinforcement? Maybe. For sure it'll at least make you feel better or give you more confidence

 

[DangItsDen]

I opted to replace the originals with the 285/70 R18 Toyo Open Country AT3 from Discount Tire. They are significantly lighter than any other of the 285s and seemed like they got a better score with low rolling resistance. First impressions are that the ride isn't as harsh as I expected, they are noisier, but doesn't bother me, they look great and don't rub so no modifications needed, although they come very close. Effect on MPG is yet to be determined. Picture below with the new shoes:

Truck looks great! I am planning to go to this set of tires in a 285/70/17 Load C. Can you update us on how you like them so far? Thanks!

 

[Barak]

I like them. Great offroad, no rubbing at all. MPG probably took a hit, but I have been towing/carrying motorcycles on the hitch carrier so I don't have a better estimate on a clean setup yet.

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