Load Ranges, Ply Ratings and Heavy Loads

If you need your tires to handle a lot of weight, Load Ranges and Ply Ratings are going to be important. Both of these indicate the tire’s strength as well as its behavior under load. Ply Ratings are especially important, not just for towing or carrying heavy loads, but also for going off road and driving at competitively high speeds. On truck tires, Ply Ratings are also known as Load Ranges.

Most of the tires you’ll see in passenger sizes are going to be what’s called Standard Load or SL. These can be inflated to 35 psi. While standard load can be designated by SL on a tire, it’s more common that they have no letters at all. So, for example, a Standard Load tire size could either be written 205/55R16SL or just 205/55R16.

Now that we’ve got the standard out of the way, let’s get into some of the other load ranges you might encounter. We’ll start with load ranges designed more for speed and performance than heavy lifting:

Extra Load (XL)

This load rating is great for performance cars driven at higher speeds, usually on private tracks. Extra load basically means the tires can handle more weight than standard tires in the same size, but typically still on a passenger scale.

They have stronger sidewalls and can be inflated to a higher air pressure (usually 42 psi), which makes them more durable. XL tires are most often found in high-performance lines because this durability makes them ideal for handling the heat and stresses of high speeds.

Light Load (LL)

Light Load passenger tires are pretty rare. These tires are the opposite of the XL tires, in that they’re designed to take a lighter load than standard tires in the same size. They’re typically used on racing and competition vehicles where the vehicles are typically smaller or lighter. So, unless you’re racing, you don’t really have to worry about this one.

That’s pretty much it for those load ratings. Now it’s time to talk about what you’ll see if you need to carry some weight.

LT Tires

Light truck tires come in a few different load ranges, and the higher the load range, the higher the ply rating. While ply ratings used to refer to the actual number of plies, todays plies are stronger so tire casings can have less. Now, instead of indicating the actual number of plies, the ratings indicate the number of plies equivalent to that stiffness and strength. For example, passenger tires will usually have a 4 ply rating, but the tires themselves may only have 2 or 3 plies in their construction, so it’s really saying they’re as strong as 4.

A higher load range also means a less flexible tire that can be inflated to a higher pressure. This is so they’re more stable under their loads. For light trucks each load range is indicated by a letter, and each letter has a corresponding ply rating and max psi. You’ll usually find the load ratings in a chart like this:

They start off with the lowest load range, which is the same as Standard Load. As you go up, the tires get stiffer and stronger. D or E are the most common passenger Light Truck load ranges. However, the higher load ranges aren’t just good for heavier loads, you would also want a higher load range for off-roading. Since the tires are stiffer and stronger they can handle unpaved surfaces (like rocks) with less danger of being damaged.

There is, of course, a downside: a stiffer, sometimes noisier ride. If it’s just a work vehicle, you probably won’t even notice. But if this is your everyday vehicle and you just haul things a few times a year, you’ll probably notice a less comfortable ride the rest of the time.

Higher load ranges can also affect performance, because they’re stiffer tires. In passenger tires it’s not too big of a deal, but with light trucks it can be a bigger difference. This is why it’s recommended you match the load range when you’re just replacing one tire.

One final note: Don’t confuse the Load Range letters with Speed Ratings. They have nothing to do with load carrying capability, and you definitely don’t want to mix that up. It’s not that hard to avoid confusion, though, as the load ranges are pretty much only what’s listed in the chart above, while speed ratings most commonly seen on vehicles are at the other end of the alphabet.