Toyota Tundra: Understanding the Difference Between LT Truck Tires and P-Metric Car Tires

J.G.
Update by J.G. Pasterjak to the Toyota Tundra project car
Jan 2, 2021

Truck tires? On a truck? That’s crazy talk.

Most half-ton pickups sold in the U.S. don’t actually come with truck tires,” says Maxxis Tire’s John Wu. And, bafflingly, he’s not wrong. Most 1500-series pickups sold in this country come standard with P-metric passenger-series tires. To get a true LT-grade tire on your new truck, you’re either going to have to go deep into the options sheet, visit an aftermarket tire dealer, or make the leap to a 2500-series pickup or beyond.

It’s just the way most people use trucks,” Wu continues. “Most pickups are basically passenger cars, or SUVs with beds. Owners might throw a couple bags of mulch or a few 2x4s in at Lowe’s or Home Depot, but mostly they’re not being used as high-load vehicles.”

And that’s the key term right there: load. Because that’s what separates a true LT truck tire from a passenger tire that just happens to fit a truck.

When we bought our 2010 Toyota Tundra, it had a lot of comfortable and pleasant bells and whistles, but we knew that 90% of its use would involve hauling a trailer with a project car on it to a race track or autocross site. The tires that the previous owner had installed on the port-accessory, 20-inch BBS wheels looked nice enough, but they were far more suited to a large luxury SUV than a truck that would actually be seeing some hauling use.

And these tires were utterly incapable of dealing with any sort of soft ground. This point was driven home at, well, our home, when the truck almost got stuck in our yard on level ground, just because the tires could get zero purchase on wet, muddy grass after some heavy rains.

While we never plan to go off-roading in our two-wheel-drive Tundra, race track paddocks do not always feature the most well-groomed surfaces for trailer parking. If we can’t even comfortably negotiate our own yard, it’s time to look for something more capable.

But did we need a “truck” tire? And what even is a “truck” tire? Is it notably different from a passenger-car tire that just happens to fit your truck? That’s where our conversation with John Wu started.

When our engineers are designing a tire—any tire, really—they have a list of priorities of things they want that tire to do,” he explains. “Ride, handling, steering response, load capacity, longevity, off-road traction, road noise: All of these factors and more are involved in every tire.”

But designing those factors into any particular tire is a lot like building a character for a video game where you have finite resources to assign to several talents. Adding extra hit points may mean you need to take away some damage ability and vice versa.

Well, the same is true with tires. “Our engineers will just reprioritize those design parameters for each tire,” he continues, “whether it’s a tire designed for track days, where grip and feedback are more important than ride and wear, or a truck tire, where load capacity is usually the prime consideration.”

When it came to our Tundra, Wu suggested a set of Maxxis Razr AT tires in LT33.5x12.5x20 to replace our P305/50R20 P-passenger rubber. The outer dimensions of these two tires are extremely close, meaning we wouldn’t have much speedometer error or fitment issues. Meanwhile, the new rubber's load capacity and design philosophy was far more industrial-grade.

Those Maxxis Razrs are designated with an F load range. That means they have the equivalent strength of a 12-ply tire from back in the day, when the load range of tires was defined by their carcass thickness, not their absolute strength. High-tech materials and construction techniques have improved tire technology to where physically thinner cross sections of sidewall with the right construction and makeup can be just as strong as the thicker, multi-ply rubber of yesteryear.

Our old passenger-based tires carried a C load range, and their accelerated wear and poor ride when towing told us a lot about why car tires aren’t truck tires. The Razr ATs are rated for a load north of 3000 pounds per tire and can hold as much as 80 psi of air, making them far more suitable for doing actual truck stuff.

True LT tires have a few other differences from P tires. “Usually, you’re also going to see a more square edge on the tread and deeper tread blocks on an LT tire,” Wu continues. “This is for a couple reasons. First, we’re trying to design the tire to have an optimum contact patch under higher loads, which is when it matters the most. And also, we can build a little more depth into the tread just to give a little more longevity before the tire needs to be replaced.”

Our first impressions of the Razr ATs, after having them mounted at our local Discount Tire, actually surprised us—and Wu—a bit. We were expecting the move from a passenger tire to a truck tire to come at a bit of a price regarding ride, road noise, and steering feel. Remember our chat about having a finite pool of ability to draw from.

But what we experienced was precisely the opposite. All of the “luxury” qualities of the truck were instantly improved after switching to the LT tires. Part of this could be due to the fact that we were replacing older tires with newer ones, or the Razr ATs could just hit a sweet spot in balancing capability with comfort.

I guess our engineers did a really good job on these,” Wu noted with a chuckle. In any case, we’re finding that with a quality set of modern LT-grade tires on the truck, we reap all the benefits of increased load and capability while losing little to none of the civilian capability and enjoyability for those times we just want to go to Taco Bell or drop the kids off at school.

Our 33x12.5x20 Maxxis Razr ATs are available from various outlets for around $325 each. LT tires are frequently priced a bit higher than similar-sized P tires, but the extra money means extra capacity for doing the things that trucks do. And that was Wu’s standard when we asked him how someone would make the decision between true truck tires or tires that simply fit their truck.

How much of your truck’s capability are you using?” was Wu’s rhetorical answer. “If you’re never putting any stress on it—just driving it like it’s a car with a big bed in the back—then passenger tires are probably a fine choice.

But if you’re using more than half the max bed capacity a couple times a month, or towing something like a car even once or twice a month, that’s kind of when I start suggesting having a tire that’s rated for the job,” he continues. “You need to pick your tire to handle your most difficult usage scenario, because that’s when you rely on your tires the most.”

For us, that means the more aggressive all-terrain tread of the Razr ATs can move our Tundra around our yard with ease, and they eat miles on the highway while towing our project cars with comfort, ease and safety.

Join Free Join our community to easily find more project updates.
Comments
View comments on the GRM forums
iceracer
iceracer MegaDork
12/17/20 9:44 a.m.

what are the load ratings of the tires vs epected gvw ?

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
12/17/20 9:50 a.m.

It's true, Toyota puts the wrong tires on their trucks. I've seen massively rapid wear on a brand new stock Tundra because the stock tires and pressure recommendations were way off, trying to make a truck feel like a Camry. Meanwhile, my very similar Tundra on Michelin LTXs running more than double the tire pressure worked much better and lasted far longer.

Sponsored by

GRM Ad Dept

Our Preferred Partners
dDqBAz4WVbICskSGuyDB4BrBZafYJk3Q6r2tp5HCen2LDNbFx3ngKhzdDIcFZGFw