Tire dealers have told me there's no difference in the "toughness" of a SL tire versus that same tire in an LT version...look at the weight carrying capacity and they are the same or really close. There aren't more plies in the LT version.
This only applies if they are the same brand, model and size tires being compared.
Anybody know this for a fact?

Horsepuckey!

I run gravel roads back from one of my farms in the summer. I will have a 90% flat rate when running standard tires, and I haven't had a flat in 6 years running LT's.

Load range "D" at minimum, "E" is even better. JMO, Dutch.

http://www.tirerack.com/tires/Spec.jsp?make=BFGoodrich&model=Rugged+Trail+T%2FA&vehicleSearch=false&fromCompare1=yes&partnum=67R7RUGTTA&tirePageLocQty=%26partnum%3D67R7RUGTTA

not sure if that link will work, but you can go to tirerack dot com and look at specs.

LT tires are around 10 lbs heavier than their matching SL tire.

Ask the dealer where they think that 10 lbs (25% more mass) went, and if htey think a 40 lb tire is as 'tough' as a 50 lb tire of the same external dimensions.

Thanks. I had trouble believing that they would be the same.

LT all the way, and if it is a heavy rig like a 3/4 or 1 ton, the E rates are the only way to go. E's hold up so much betetr than Ds.

Alos, I learned something interesing. I had a set of D rated 285/75R16s (16x8" wheels) on my 2002 Dmax. They gave it 7 3/4" clearance under the rear diff. My 2009 came with 265/70R17 E rated tires (17x7.5" wheels), which are nominally 1.2" shorter. This should equate to .6" less clearance under the rear diff than with the 285s. However, the 265/70R17s give me 7 5/8" under the read diff. In other words, the D rated 285 squished down almost a 1/2" more than the E-rated 265s.

That is most likely because the Es are a 80 psi tire while the Ds are a 65 psi tire. So in this case, all the 285 Ds did was give me more rolling resistance without a significant increase in ground clearance over the 265 Es.

I understand what you are saying. Something else to consider is that even tires of the same "size" are not always the same diameter...some in say, size 265/75-16 can be almost an inch taller than others that are also 265/75-16...I've seen four tires of the same 265/75-16 size sitting side by side and there was about an inch difference in height from the tallest to the shortest.
Looking at different tires is fun and interesting, but after a while I've concluded that there's a boxful of lugs/tread blocks somewhere, and makers just pull however many shapes they need out of the box and put them together in whatever combo they want for a tire tread design. No tires are much different to look at than any of the others, within types.

The number of plies thing is mostly meaningless nowadays. It goes back to the old bias ply tires when an E rated tire had 10 plies, a D had 8 plies, etc. Today everything's radials and it no longer applies, but folks still refer to an E rated tire as a 10 ply. All other things being equal, an E rated tire will still be heavier and tougher than a D rated one, which will be heavier and tougher than a C rated one etc.

My 3/4 ton dodge diesel came with E rated tires and I've kept the same rating tires on it. I rarely have flats or any other problems out of the heavy duty tires. I always seemed to have problems out of the standard tires I've run on other vehicles. In my experience the LT tires last longer and give much fewer problems than the standard tires. To me it's a no brainer to use them on a pickup.

Do you know what happens if you inflate a standard tire to the same air pressure of a truck tire of the same size? If they're the same, why does the LT handle so much more?

How are LT tires built differently than SL tires of the same weight-carrying capacity, size and make?

I don't know about internal construction, but most P rated tires are load range B. LT's start at C and go on up. They're heavier because of the added material in them. Normally the tread is much thicker and they don't have as much flex in the sidewalls.

That's what I see, too. Even in the smaller light truck/ standard load sizes there's around a three pound difference. There's got to be more rubber in there somewhere.
What I found on one website (Toyo Tires) that I thought was interesting was that in the same size tire, an LT will take more air pressure to carry the same weight as a SL, so the ride will be harsher. But like you said, the LT has the potential to carry more weight than the SL.

Those tire dealers need to find another line of work because they don't know what the hell their talking about.

Bill

What do you know about it? Care to share? I'm trying to learn something about tires, and would like to know why you feel the way you do about the difference between LT and SL tires.

pretty much what others have already said.

Max load is usually the same, unless going from a C to a D load rated tire, or from a D to an E.

Otherwise the difference is that LT tires usually have a little more rubber in the sidewalls for stability under load. They often also have slightly deeper tread.

While the max load for both tires may be the same, the LT will carry that max load easier and safer.

As someone else said they also resist puncture better in my experience.

Bill

Thanks.

A little off topic, but we were having blow out problems with the 15" tires we had on our race car trailers. One trailer was also giving us fits with the outside bearing on the 5200# axles. The trailers are loaded right at their capacity. Actually, mine is about 2000#'s above.

My dad's was the one that was having the bearing and tire problems. We found a very simple way to upgrade the axles (Dexter) to the 7000# bearings and 8 lug hubs. All we had to do was swap out the hubs/drums for the 7000# version which cost approximately $340 total and then we were able to put LT235/85r16 Goodyear G614 G rated tires. These and the wheels are rated at 3750#'s each at 110#'s of pressure cold.

One of the advantages of these LT tires over the ST tires is that we can drive over 65 mph. I believe these are rated to 75 mph, but I know it is at least 70 mph which we stay at or below. I also realize this thread was comparing SL to LT. Just thought I would mention our recent upgrade.

That's interesting because when I bought a 12k flatbed I was asking about the difference between the 12k and their (Top Notch Trailers) 10k trailer. They said just the 6-hole vs 8-hole hubs and the tires and wheels... the axles, spindles, bearings and springs were the same. For $200, I went with the 12k; but I know it can run around $1,000 if you have to upgrade to heavier axles after you've already got the trailer.

I didn't know that about the speed rating on trailer tires.

I can't speak for the difference between the 6000# and the 7000# axles, but I know for a fact that the outside bearing on a 5200# axle is smaller than the one on a 7000# axle. All three of them use the same spindles and brakes. Maybe the 6000# axle has the larger outside bearing, but we wanted the larger outside bearing and the 8 lug wheels which meant we needed the 7000# hubs. They work great!

ST rated trailer tires have a 65 mph limit. I didn't know that until this year.