Allow me to tell a story from my days at working for a major tire manufacturer. A guy came into the corporate headquarters with a damaged truck. It was a dually. He wanted us to pay for the damage, about $3 grand. He had replaced his LT tires with the same size P tires and one failed, causing the damage. He had ordered tires from Tire Rack and mounted them himself. Why he didn’t notice that the tires said max pressure 44 psi and his placard called for 65 is still a mystery. We offered to replace his tires with the right kind and to pay his deductible if he agreed to turn the claim into his insurance company.
That could have easily been worse for him. That’s why I think there needs to more of a difference!
All things being similar, I think you will find that a “P” (Passenger…), “SL” (Standard Load), and “LT” Light Truck) tires vary in three important ways: Load Rating, Tread Depth/Design, Tire weight, and Price…
P (Passenger) tires are designed for everyday cars, minivans, crossovers, and light-duty SUVs. They prioritize a smooth, quiet ride, fuel efficiency, and highway traction. P tires are designed solely for the lighter gross weight of standard passenger vehicles. P tires weight from 18 up to 35 pounds on average…
SL (Standard Load) Tires: Often have no letter at the beginning of the size, or explicitly list “SL”. They share similar everyday-driving goals to P tires but are generally rated to carry the standard weight of half-ton pickups, SUVs, and crossovers. However, the category gives them away with names like: Highway All-Season, On-Road All-Terrain, Crossover/SUV Touring All-Season, etc… trying to be all-thing for all purposes… They often have a more “aggressive off-read” tread design than P tires, but not too much as to maintain smooth, quiet service. SL tires weight up to 47 pounds on average…
LT (Light Truck) tires have thicker, stiffer sidewalls to resist punctures from rocks and sticks. P-tire sidewalls are thinner and more flexible, which aids in a comfortable ride but makes them vulnerable on rough terrain. LT tires are constructed with heavier materials (often 8- or 10-ply ratings) and higher inflation pressures to support massive weight. LT tires weigh up to 55 pounds on average…
P type tires come in 2 varieties - Standard Load (SL) and Extra Load (XL). The difference between the 2 is the max load - the XL carrying more load due to using more pressure.
P type tires refers to a particular load table developed by one of the tire standardizing organizations, such as the US based Tire and Rim Association. P type tires are designed for lightly loaded vehicles operating on standard highways - such as cars, light duty pickups, light duty vans, minivans - that sort of thing.
LT tires come in Load Ranges - C, D, E, etc. - and are designed for use on medium duty pickups and vans. They carry more load than P type tires because they use more inflation pressure. This also refers to a load table applicable to the service conditions.
Well, I still think it’s OK if there are P-rated and LT-rated tires out there that match in size.
What there needs to be is both educational resources, such as yourself, and, physical documentation, such as physical posters and on-line info, to ensure that not just customers, but also shops and tire sellers, are not putting just anything on Light Truck-class vehicles.
The issue is not having P-metric, SL and XL, and LT tires that are all for example ‘225/75R15’.
It’s common for people to buy a new truck that takes an LT tire but never use it as a truck for hauling and drive perfectly safe with P rated tires. This is extremely common around here.
I think some have missed the part (as in Mr Capris post) that in a P metric tire, you either get a SL standard load or an XL extra load, meaning SL and XL are both P metric’s tires, and then the LT tires in the C, D, E etc etc…
How do the tires end up on the truck? Do the drivers have their own mounting/balancing equipment? When I was shop manager or when I ran my own place, if the door tag specified LT, we would only mount LT tires.
Full story is kind of complicated. You all do remember COVID caused chaos at the car dealer? I needed a 2500 level duty truck for a heavy travel trailer and could not find one with a diesel anywhere. So my dealer contacted Ram directly and spent time on the phone and ended up with the proverbial unicorn: a 1500 Ram Big Horn EcoDiesel with heavy duty tow and cargo package not otherwise available. While its a model 2021 it is really a mix of 2020 and 21 option parts (thanks Covid). In addition to regular towing package bits it has reverse trailer steering with multiple cameras, stiffer rear shocks with a one off factory air-bag rear suspension. It also has several other electrical and mechanical options that make my truck a bit more heavy duty than your run of the mill 1500 Ram. It can tow 12,000 lbs and carry 1,800 lbs but it lacks a couple of featured options, like its tow mirrors can’t be electrically folded in. My dealer dealt directly with Ram reps to confirm that the truck would have a cargo weight capacity close to a 2500. It came with the wrong tires AND capacity plate. There was no recall because it was a special order and literally the first and only truck they built with the combination of options it has. The order sheet had the correct tires and wheel options but then things got weird when the truck was delivered without any documentation at all. In fact my poor salesman had no idea my truck had been delivered for 3 days while management tried to figure out why they had a truck without documentation that was not in their computer list of deliveries. It also showed up two weeks before the scheduled delivery date. Things got even weirder… The dealer handed me the keys, only to never tell my credit union that I had taken delivery. I went 6 months without a car payment despite multiple calls and emails to both dealer and bank. I had a truck with a VIN but no manufacturer’s certificate of origin, no title and temporary registration after temporary registration for 6 months. The family joke was: “Dad, why are you calling the bank and dealer… just drive the thing for free until they catch on”. It took 6 months for all the documentation to show up. And it wasn’t until we got all the paperwork that my service guy realized the tires were wrong, but by then they’d had nearly 20,000 miles on it… yeah that truck got driven across the country several times.
Our BRT (Big Red Truck) has now has 108,000 trouble free miles of smiles.
Yep. And what customers should understand is that an XL P-metric is no substitute for a LT tire.
I ran sound for a relatively poor Pentecostal church a half hour from where I used to live in CT. Until 7 years ago they owned a Dodge 2000 3500 Maxiwagon van, 15 seater that they cobbled along all those years.
That should immediately explain how P225/75R16 tires ended up on that thing. Correct size, wrong category.
After I brought it up to the Pastor, they eventually had the LT of that size installed.
And Capri can take it from there, but I will allude to construction differences, not just load figures, that make LT the better choice in such scenarios.
