Determining safe tire load rating required

[YYC]

Hello. I am trying to determine the appropriate load range tire for my setup and intended use. I have a 2012 Tacoma DCSB 4wd that will be hauling a FWC Falcon slide-in camper. Truck/camper usage will be about 60% on winding mountain highways, 30% on unimproved fire/gravel roads and 10% mild off-road. Fully loaded the rig will weigh 6500lbs. Given the truck's weight distribution, I could have about 3900 lbs on the most heavily loaded axle, or about 1950 lbs per tire.

If I de-rate a P or ISO-metric tire (265/70R17) with a 115 load rating by 10% for light-truck use (as is required) I get around 2430 lbs capacity per tire. "C" load LT tires are also about 2470 lbs. That works out to around a 25% safety margin when compared to the 1950lb load per tire.

So here is my question; I am not sure if that 25% is adequate or not? Does anyone know if there a standard tire capacity safety margin? When I compare the GVWR of my Tacoma vs. the OEM tire load rating, the safety margin (of max truck weight vs max tire capacity) is more like 50% and on my F150 it was 42%.

I'd like to avoid the weight and ride penalties of 10 ply LT tires on a lightweight Tacoma, however being safe is more important.

Thank you.

 

[Mickey Bitsko]

Here's a great idea, call a reputable tire shop.
You should be more concerned about being overweight
On your' LIGHTWEIGHT TOYOTA TACOMA 'than a set of tires..smh

 

[Winterhawk]

A quick search says your GVWR is between 4650 and 5500 depending on the model. Maybe I'm wrong and I hope so, because you're 1000 over that if true. That aside, the tire tables are an industry standard and you'll be fine as long as your below the stated rating. As far as load range E goes, I personally don't see much of a comfort penalty if any when daily driving. When off highway I do notice a harsher ride, but lowering the air pressure some takes care of that.

 

[MontySquareo]

i use load range E tires on my Montero (that's what it came with from the previous owner) and would recommend running them. i haven't been able to pop them yet, running them on sharp rocks, and you can just let some air out for comfort. highways are usually smooth enough that hard tires don't matter.

 

[Buddha.]

I had 235/85r16 load range E on my Ranger and didn’t think they were too rough. The narrow size kept the weight down a bit too I think.

 

[charlieaarons]

Since virtually 100% of tires are radial unless you go way out of your way to buy Super Swampers (and they make those in radial also), there’s very little ride difference between different load ratings of a given tire model and size. All sidewalls are designed to be flexible. Even huge 53” military tires, are 1 ply steel; 4 plies in the tread.
LR E tires MAY have a small amount of extra rubber in the sidewalls, and obviously traction treads have a greater moment of inertia (dI = r**2 dm).
Even if the Ranger with 235/85R16s has steel casing Michelins, it rides decent because the tire air volume is big for the weight of the truck.
For best ride and traction, get the smallest wheel that will fit over the brakes.
My opinion of lifted light 4wds (pickups etc) with 22-24” wheels is unprintable. For several good reasons for anyone who’s actually going to use it for more than mall cruising.
Bottom line: overkill is good on tires as far as load capacity. Lightweight passenger tires are better for autobahn cruising but not for bad roads.

 

[Trestle]

Pick the tire you want, and reach out to the MFR for inflation pressures for said tire and size for both C and E. If there is a difference, go with the higher load (as it will likely allow less pressure for a given weight). If there is NOT a difference, then a C should be plenty for your weight and you incur less rotating mass (usually) for less of an accelleration/decelleration/MPG hit.

Example for my heavy truck was an E rated tire allowed me (per the MFR) to run 15 less PSI vs. the same size tire in a D rating. This translated into a more compliant ride.

If you have multiple tire model candidates, you may have to do it with all of them. Note: Some tire manufacturers have this published already, others you will have to reach out to them to get the info. Most will actually respond, though it may take a few days. If they don't respond, my suggestion is to find a different brand anyway as their presale support should be at least as good or better than their after sale support. i.e. If they treat you like crap now, then why would they treat you any better after you spend your coin on them.

 

[Metcalf]

At those weights, you don't want a C rated tire if you are going to see anything off pavement, and you won't feel any ride difference. Any tire weight penalty will be worth the longer life and extra margin when operating off the pavement.

Running the truck off-road 1000lbs over GVWR is a pretty bold move. I know back in my Wildland Firefighter days, I went rounds and rounds with the BLM as an engine boss trying to get them to pull weight back out of F350 based type 6 fire engines. We saw DRASTIC decreases in tire, service, axle, and suspension issues getting the weights back under GVWR.

 

[plainjaneFJC]

No way I’d run P tires with a camper on that truck. Really no way I’d run P tires period on a truck

 

[86scotty]

If I'm loading up a camper or truck with camping things, people and gear it's going to have E rated tires on it, especially if I'm off-roading, which is what I do with any truck I own. My light Jeep JLU is the only thing I have owned in years without E-rated tires and that's just because it's a light Jeep.

E-rated tires are tougher, shed heat better and don't have any disadvantages at all that I know of. You can run them at lower pressures for more comfort and they do fine. I typically run heavy camper vans/trucks with E-rated tires at about 50-60 PSI (on road) and they do great.