Lotsa threads on tires and tire sizes got me wondering...

I searched the web and found a lot of good info on tire sizing, how to 'read" a sidewall, etc... But there's one question I can't find an answer to.

All the websites I found on how to read tire sizes simply say: "A 'P' rated tire is designed for use on a passenger car and an 'LT' rated tire is designed for use on a light truck." They don't say why, or what the difference is.

So, what's the difference? If I put "P" tires on my light truck, will it suddenly want to park at the mall, and shun other trucks? Will a Buick that's been fitted with "LT" tires suddenly desire to hang out with F350's at construction sites?

Seriously though, I would guess it's got something to do with sidewall strength and/or max load-carrying weight limits, or maybe tread aggressiveness/depth. Anyone know? And by the way, as long as I'm asking questions, would an "X" be considered a "light truck" since it's on a truck frame, or are they talking about rigs like F-250's and the like?

the xterra would be considered a light truck, as it's built on a frontier platform and the term "truck" doesn't just mean a vehicle with a 6 foot bed, etc. you'll also commonly see the tires as light truck/suv tires.
as far as the lt and p ratings, i'm guessing you're right about the weight, tow capacity. another possible difference is the max speed that each tire can take before becoming dangerously unstable.

Yup, usually tires with LT rating have extra ply(s) on the sidewall making it more resistant to puncture and just more rugged overall. It also tend to give a better load capacity than a similarly sized P rated tire.

I've been told by tire shops that the X is rated as a "light truck." That being said, you can still put P rated tires on the X. The tires won't suddenly explode if you hit a bump or something. You just may be more susceptible to getting a puncture if you go offroading on trails with a lot of jagged rocks and boulders.

The stock grabbers that came with my xterra are "P" rated tires. With most manufactures LT just means that there is more plys so the tire can take more abuse or carry heaver loads.

In most cases P rated tires will give you a softer ride than the heaver constructed LT tires.

A hit that would puncture the sidewall of a P rate tire may ony put a nasty gash in a LT tire. The LT tire could save you from a inconvente flat, but you still may have to replace the tire for the truck to pass inspection.

There is nothing wrong with using a P rated tire. It is more a matter of what your needs are and what you expect to do with your xterra.

P-metric tires used in Light Truck (LT) applications must have maximum rated load reduced by 10%

Brent