Recommended pressure for Grabber ATx E-rated on an OR.

I posted this on the Wheels and Tires forum and got 35 views and no replies so I'll try it here.

On my current Cooper discos STD load range I've set the pressure to 30 psi and after 23Kmi the tires were cupping. I called the place where I bought them (Big-O) and he said they should be at 35 psi. I'm about to put on some General Grabber ATx LT245 R75 16 and was wondering what pressure folks are running those at. Tons of snow here in CO so the chalk test is out. I'll be installing a camper shell (Ovrlnd) in April and building some cabinets. My guess is the total weight in the bed will be around 500-600 lbs.

I ran the OEM and LT tires through the tirepressure.com and tiresize.com calculators and the results for the LT tires were 50 psi and 46 psi, respectively. I don't know what givens are assumed for the calculations. Truck operating at max GVW?
Thanks, Tim

 

I have Falken Rubitrek LT 235/85/16 load range E on my 8500lb 3/4ton Dodge diesel pickup+camper, 75psi, probably run 65psi if no camper as the empty truck weighs around 5600lbs.

My point is: LT load range E is overkill for a Tacoma.

 

I hear you on that. My thing is I live in CO and drive FS back roads here and in Utah. Also I'm planning on driving an Alaska next summer (if the border is open), hitting the Demspter highway all the way to the Arctic Ocean and the Denali highway. Probably a bunch of back roads in BC and in the Yukon and NW Territories. I've encountered a couple of slow leaks on two different SL tires that had plenty of tread life remaining. So given my history with SL tires I'd like something beefier. There's a sticky in the wheels and Tires forum and some folks with Es seem to settle on 35 psi. Just wondering how the 3rd gen forum thinks....

 

When I worked for a logging contractor we ran 48psi on LT tires on 3/4ton pickups to reduce punctures from sharp stones on the gravel logging roads.

 

I also have E rated tired. Wildpeaks. They are not overkill. It's personal preference. I've also had issues with lower rated tires here in Montana due to the trails and crappy roads. Also having tons of snow, so the chalk test is out for me too. Currently set to 35ish, but I checked this morning cold and it was 33. I am not loaded. I have maybe a couple hundred pounds and that includes a full size spare.

 

E rated isn’t overkill for a tacoma. So tired of hearing that.

no one thinks they need e rated for load rating, they want it for puncture resistance and strong sidewall that can handle airing down and heavy chains.

If you use your truck like a truck LT tires are a good idea. C rated tires are not a common offering, and E rated tires aren’t much heavier. Where’s the downside?

I’d start at 40psi, and go from there. Probably going to be happy between 38 and 45.

 

My brother has about the same Dodge setup as you. His camper is a home-built unit on a flatbed. Unless someone has a better setting, I think I'll start out running them at 40 psi and keep a close eye on the tread depths. They're being delivered tomorrow or Wednesday so they're bought. I looked around for C-rated tires and didn't see a whole lot of options in a size similar to the OEMs. The nice thing about going to the 245 75r 16s is that they the same diameter as the OEMs so there's no Speedo/Odo correction and they're only 7 lbs heavier than my Discos. Shouldn't have a big MPG hit.

 

Sounds counterintuitive

 

48 is "low" for a 3/4 so it kinda makes sense.

 

The traveling on pavement part of going to and from work was not paid by the employer so there is no way we were stopping to air up or down, so 48psi was the all around gravel and pavement psi.

 

I have the General A/TX's in 265/75-16 and E load rating. I emailed General tire support with same question and their response was to inflate to 36 PSI. If you look at the Toyo Tires load vs pressure tables (page 21), you will see 35PSI corresponds with 1910 lbs of load - much higher than what Tacoma's need, but consistent with the practice of inflating LT-E tires 20% higher than non LT tires. My base load is 6250 lb day-to-day and 6600-6700 fully loaded for overlanding, due to: Alu-cab canopy, ARB awning, drawers, skid plates, bumper, Warn winch, rock sliders, LRA fuel tank, roof top tent.

After 20K miles wear is slightly more in the center than edges of thread, indicating slight overinflation. I am happy with 36PSI, as it provides a good balance between ride quality and not being too soft steering in corners. When going extended distances on highway, I inflate to 40 PSI to improve MPG slightly.

(https://www.toyotires.com/media/2125/application_of_load_inflation_tables_20170203.pdf)

OP: the tables above show, for your 245/75-16, a load capacity of 1700 lb @35PSI, or 3400lb per axle at 35PSI. The Tacoma rear axle max load (GAWR - gross axle weight rating) is 3280 lb (for my TRD-OR model), so I would say 35 psi will be just right for you if you do not plan to exceed the GAWR in the rear.

 

Thanks Phillip, Your experience is what I'm looking for. My load will be slightly less than yours since I don't have a heavy-duty bumper, winch, sliders and the extra tank. Looks like 35 lbs might be a good starting point and then adjust according to tire tread wear.

 

I'll second @PLavee

I have the same size Grabbers. I've been running them at 34-36 after what little bit of research I've done.

 

Thanks DT..

 

E loads are tricky to balance between ride comfort and not overheating them by under inflation. I run my Toyo RTs around 38 and so far so good.

 

I run my 285/75r16's at 32/31 even though both Toyo and Cooper have suggested no less than 35. If I have added weight for whatever reason I bump them up.

 

35 “cold” in summer for efficiency and even tread wear on pavement. 30 in winter for more traction.

 

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