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04-22-2017, 05:43 PM
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#1
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1 Rivet Member
1966 24' Tradewind
Vancouver
, British Columbia
Join Date: Jan 2017
Posts: 5
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Maximum PSI and Tire size
Hello all
We’re presently in a small town in Mexico. A few nights ago we hit some concrete and damaged the side wall on one of the tires for our tow vehicle, a 2008 Ford E350. We’re pulling a 1966 Tradewind.
Much to our relief we found 2 new replacement tires at the local tire shop. Well, I was relieved until I decided to check the air pressure a few hours ago.
As it turns out the new pair of tires don’t have the same rating as the old ones. We originally had a set of 4 Michelins, LT245/75R16 120/116R, maximum PSI is 80. The new tires are Fuzion LT245/75R16 111T maximum PSI is 44. which we now have on the back. When towing we’ve always had 80 PSI on the back tires and 55 on the front as per Ford’s specifications.
So far we haven’t done any towing with these new tires but we’re set to travel again on Tuesday.
There may be a chance of getting something new before then, but if not, what are my best options? Would it make sense to put the Michelins on the back as they can take the higher psi even if they are the older tire (3 years). As i understand it if you don't have 4 identical/same age tires, the older ones would normally go on the front.
Thanks!
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04-22-2017, 07:30 PM
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#2
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4 Rivet Member
Vintage Kin Owner
St. Louis
, Missouri
Join Date: Jul 2016
Posts: 415
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Unless your 3 yr old tires are compromised in any way, they should do fine on the back. Thought I heard the best tires go on the front. In your case it may be a toss up which tires are "better".
Put the stronger tires on the back, and you should be fine.
__________________
The Morgans
1989 Avion 34VB
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04-22-2017, 07:52 PM
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#3
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Rivet Master
Currently Looking...
Mantua
, Ohio
Join Date: Jul 2005
Posts: 7,062
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The 116r and the 111t are your weight ratings. Look them up on the Internet, the higher the number, the higher the weight rating. Might want to check to be sure. What does the sidewall weight ratings indicate?
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04-22-2017, 08:27 PM
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#4
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Moderator
2004 30' Classic Slideout
Fenton
, Missouri
Join Date: Mar 2002
Posts: 10,401
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The weight rating is the critical factor and in this case you will probably find that the weight rating of your new tires is about 677 lbs less per wheel than your old tires. That's a lot of the reason why those new tires carry significantly less pressure. My greatest concern is with your camping load and trailer hooked up, what will be the weight that that axle with the new tires is carrying? If it is more than 4,818 lbs, you are going to be overloading those tires.
Jack
__________________
Jack Canavera
STL Mo.
AIR #56 S/OS#15
'04 Classic 30' S.O.,'03 GMC Savana 2500
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04-23-2017, 04:38 AM
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#5
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Rivet Master
2014 31' Classic
2015 23' International
2013 25' FB International
Apache Junction
, Arizona
Join Date: Sep 2012
Posts: 6,214
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I think the higher load rated tires need to be on the rear due to tongue weight and the other gear in the bed. Get the proper tire size ASAP and probably put on four new tires.
__________________
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC
TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell
2014 31' Classic w/ twin beds, 50 amp service, 1000 watt solar system, Centramatics, Tuson TPMS, 12" disc brakes, 16" tires & wheels
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04-23-2017, 06:35 AM
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#6
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CapriRacer
I'm in the
, US
Join Date: Sep 2012
Posts: 989
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Quote:
Originally Posted by Jase
Hello all
We’re presently in a small town in Mexico. A few nights ago we hit some concrete and damaged the side wall on one of the tires for our tow vehicle, a 2008 Ford E350. We’re pulling a 1966 Tradewind.
Much to our relief we found 2 new replacement tires at the local tire shop. Well, I was relieved until I decided to check the air pressure a few hours ago.
As it turns out the new pair of tires don’t have the same rating as the old ones. We originally had a set of 4 Michelins, LT245/75R16 120/116R, maximum PSI is 80. The new tires are Fuzion LT245/75R16 111T maximum PSI is 44. which we now have on the back. When towing we’ve always had 80 PSI on the back tires and 55 on the front as per Ford’s specifications.
So far we haven’t done any towing with these new tires but we’re set to travel again on Tuesday.
There may be a chance of getting something new before then, but if not, what are my best options? Would it make sense to put the Michelins on the back as they can take the higher psi even if they are the older tire (3 years). As i understand it if you don't have 4 identical/same age tires, the older ones would normally go on the front.
Thanks!
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Jase,
You have a major problem. Get those tires off!! They are not designed for a heavy duty van. Those are passenger car tires! What you need is Load Range E tires - it will say so on the sidewall. Those are Standard Load tires (it also says so on the sidewall)
Hopefully you can resolve this before you move on - BUT - if you need to move on, do it slowly - 35 mph - and do not go more than the next town to find a shop that will have what you need.
Also, those new tires should go on the front until you get the right kind. This is the opposite of the norm, but this has to be done for loading purposes, not the usual wet traction reasons.
Why?? First look at your vehicle tire placard. It's on the driver's doorframe and it tells you the original tire size and the proper pressure for that size. Tire Guides says your truck will say LT245/75R16 Load Range E inflated to 55 psi front / 80 psi rear. Note both of those are above the maximum for those new tires.
Further, that new tire doesn't have the letters LT in front of the size. It likely doesn't have any letters at all!
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04-23-2017, 01:50 PM
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#7
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3 Rivet Member
1965 24' Tradewind
almena
, Wisconsin
Join Date: Jul 2014
Posts: 170
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Tire pressure!!!
Hello!!! I presently run LT265/75R16s on '94 Chevy 1 ton Crewcab longbox. Tires are rated at 3415 lbs single load rating at 80 psi. I pull a '65 Tradewind with the truck box loaded with motorbikes, generators, tools and everything else. Run 'em at 50 psi all day long everywhere 70+mph. No issues!!!!
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04-23-2017, 09:03 PM
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#8
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1 Rivet Member
1966 24' Tradewind
Vancouver
, British Columbia
Join Date: Jan 2017
Posts: 5
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Thanks to all for your responses. My plan always was and is now all the moreso to get 4 new tires all the same. That said, I just had a conversation with someone who came highly recommended, who suggested that all I needed to do was to put the 80psi rated tires on the back, they’re load rated at 3042 lbs. and the new ones, load rated at 2403 lbs on the front. He said my Equalizer weight distribution system would take care of the rest. He thought I was over thinking things but also acknowledged the importance of not just having the right equipment but also feeling confident with what you've got. I tend to be a "by the book" kind of person so tomorrow I'll be going to a different tire shop that he recommended.
In the meantime, if someone can recommend an online axle load calculator I’d appreciate it. I've found a few on line, some of which seem a bit different than the others, so uncertain which is the correct one to use.
Thanks again.
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04-24-2017, 06:13 AM
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#9
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CapriRacer
I'm in the
, US
Join Date: Sep 2012
Posts: 989
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Quote:
Originally Posted by Jase
Thanks to all for your responses. My plan always was and is now all the moreso to get 4 new tires all the same. That said, I just had a conversation with someone who came highly recommended, who suggested that all I needed to do was to put the 80psi rated tires on the back, they’re load rated at 3042 lbs. and the new ones, load rated at 2403 lbs on the front. He said my Equalizer weight distribution system would take care of the rest. He thought I was over thinking things but also acknowledged the importance of not just having the right equipment but also feeling confident with what you've got. I tend to be a "by the book" kind of person so tomorrow I'll be going to a different tire shop that he recommended.
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No, no, no, no, no!!!
Those new tires do not have enough load carrying capacity. Because those new tires are P type tire, you have to derate them by a factor of 1.1 - so the real load carrying capacity is 2185# - and the original tires (LT245/75R16 Load Range E) have at 55 psi a load carrying capacity of 2335# - that 150# short PER TIRE.
You need to get this fixed.
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04-24-2017, 08:46 AM
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#10
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1 Rivet Member
1966 24' Tradewind
Vancouver
, British Columbia
Join Date: Jan 2017
Posts: 5
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Hi Capriracer
I don't think I was very clear in my last post. I do plan on taking care of this. While the person I spoke with yesterday did give me some hope which I wanted to run by people here, as I said I tend to be a "by the book" person, meaning yes, its just a question of locating the right tires.
I do appreciate your input, but I don't know why you're saying these tires are P when as I indicated in my first post that they are LT245's.
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04-24-2017, 09:04 AM
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#11
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Rivet Master
1988 25' Excella
1987 32' Excella
Knoxville
, Tennessee
Join Date: Oct 2010
Posts: 5,095
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I think you will be fine for a while. I would put the heavy tires on the back and run it until I got to a decent tire shop. I curbed a sidewall in upstate NY 2 summers ago and ended up waiting 2 days for Sears to get a set shipped in. Ended up replacing the full set. Not sure the tires are overloaded but even if they are that does not mean immediate failure. I have had and have see a couple of tire failures and would much rather have one on the front than the rear. But I do not think you are in immediate danger of having one. Watch pressures, termperatures, speed as usual.
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04-25-2017, 03:42 AM
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#12
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CapriRacer
I'm in the
, US
Join Date: Sep 2012
Posts: 989
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Quote:
Originally Posted by Jase
.... but I don't know why you're saying these tires are P when as I indicated in my first post that they are LT245's.
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First, look at the size written on the sidewall. There will not be the letters "LT" in front of them. In fact, there won't be any letters at all. They are Eurometric P type tires - and in Europe, they do not use letters in front of the tire size to indicate the type of tire.
How do I know this? The first clue was the max pressure. P type tires have a max pressure of 35, 44 or 51 psi. LT tires have a max pressure of 50, 65, or 80 psi (or at least radials do!)
Second: LT tires have a dual load index, like this 120/116S. P type tires have a single load index, like this 111T.
I verified this by going to Tire Rack and seeing what Fuzion had available in a 245/75R16 - and I found the exact specs - in a Eurometric, but nothing in an LT.
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04-25-2017, 08:44 PM
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#13
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4 Rivet Member
Vintage Kin Owner
St. Louis
, Missouri
Join Date: Jul 2016
Posts: 415
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Quote:
Originally Posted by CapriRacer
P type tires have a max pressure of 35, 44 or 51 psi. LT tires have a max pressure of 50, 65, or 80 psi (or at least radials do!)
Second: LT tires have a dual load index, like this 120/116S. P type tires have a single load index, like this 111T.
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Really?
I'm riding on Michelin Defender LTX M/S tires. They are 275/65R18 116T Max pressure 44 lbs. With a max load of about 2800# they are more than capable of carrying any load I could possibly put on them.
You're saying they're not LT tires?
How much more carrying capacity could I possibly need?
__________________
The Morgans
1989 Avion 34VB
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04-26-2017, 05:43 AM
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#14
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CapriRacer
I'm in the
, US
Join Date: Sep 2012
Posts: 989
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Quote:
Originally Posted by Alluminati
Really?
I'm riding on Michelin Defender LTX M/S tires. They are 275/65R18 116T Max pressure 44 lbs. With a max load of about 2800# they are more than capable of carrying any load I could possibly put on them.
You're saying they're not LT tires?
How much more carrying capacity could I possibly need?
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The term "LT tires" refers to a particular load table published by The Tire and Rim Association. Tires in that table have the letters "LT" in front of the numbers in the size.
By contrast, Tire and Rim publishes a table where the tires have the letter "P" in front of the tire size - called P metric - and commonly grouped with similar European and Asian tires in what I call P type tires. These are frequently called Passenger car tires since that is their most common usage - HOWEVER, the larger P type tires are usually used on SUV's and 1/2 ton (and smaller) pickups and vans. This is what you are referring to.
The problem being discussed in this thread is that there are some "sizes" where the numbers are the same, but the load carrying capacities are quite different. In this thread, a 245/75R16 SL (Eurometric P type) has a load carrying capacity of 2403#, but when used in a "Light Truck" application has to be derated to 2185# - where an LT metric LT245/75R16 LR E has a load carrying capacity of 3042# at 80 psi.
I hope that was clear enough. The vehicles involved don't always line up exactly according to the way the tires are classified.
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04-27-2017, 04:42 PM
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#15
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4 Rivet Member
Vintage Kin Owner
St. Louis
, Missouri
Join Date: Jul 2016
Posts: 415
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Quote:
Originally Posted by CapriRacer
By contrast, Tire and Rim publishes a table where the tires have the letter "P" in front of the tire size - called P metric - and commonly grouped with similar European and Asian tires in what I call P type tires. These are frequently called Passenger car tires since that is their most common usage - HOWEVER, the larger P type tires are usually used on SUV's and 1/2 ton (and smaller) pickups and vans. This is what you are referring to.
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If the payload of a truck is over 2000 lbs, doesn't that make it a 1 ton pickup?
Toyota Tundra is not available in "1/2 ton" capacity. They only offer trucks in 3/4 to 1 ton capacities. Toyota sells the Tundra with either P275/65R18 or P275/55R20 tires. Is the Michelin LTX P275/65R18 tire's capacity of >2400 lbs insufficient to support a 1 ton truck with a trailer?
__________________
The Morgans
1989 Avion 34VB
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04-28-2017, 05:40 AM
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#16
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CapriRacer
I'm in the
, US
Join Date: Sep 2012
Posts: 989
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Quote:
Originally Posted by Alluminati
If the payload of a truck is over 2000 lbs, doesn't that make it a 1 ton pickup? ......
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That's another odd thing - It doesn't!
Further, an F-150, and a C/K1500 are both 1/2 ton. None of these numbers seem to line up with anything!
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04-28-2017, 07:28 AM
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#17
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Rivet Master
1988 25' Excella
1987 32' Excella
Knoxville
, Tennessee
Join Date: Oct 2010
Posts: 5,095
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I believe Mr. Morgan is just having some fun with us.
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04-28-2017, 02:07 PM
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#18
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Moderator dude
1966 26' Overlander
Phoenix
, Arizona
Join Date: Apr 2002
Posts: 7,497
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At one time (over 50 year ago) the designation of a 1/2 ton truck meant something specific.
Now it is more of a marketing term than anything else. Generally a 1/2 truck is lighter duty than a 3/4. And a 3/4 is lighter than a 1 ton. And as everyone knows there is a lot of overlap depending on the job to be done.
Towing, hauling or just moving around. The rating of the truck is dependent on engine, axle, suspension and body style.
>>>>>>>>>>>>>>>Action
__________________
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!
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04-28-2017, 10:30 PM
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#19
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4 Rivet Member
Vintage Kin Owner
St. Louis
, Missouri
Join Date: Jul 2016
Posts: 415
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Quote:
Originally Posted by Bill M.
I believe Mr. Morgan is just having some fun with us.
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Not really.
If you learned everything you know about trucks in 1982, then these conversations are mostly pointless. Today's trucks are simply not the same as they once where. The only reason Ford still uses the moniker "F-150" is name recognition. The minimum F-150 payload is up 400 lbs since ten years ago, making it AT LEAST a 3/4 ton. Regardless our affection for the trucks we used to drive, today's 150 easily out performs yesteryear's 250.
I like to believe I can still learn a thing or two. After following this thread, I discovered my Defender LTX tires are not LT tires. I learned a little of what genuine LT tires really are. In the process, I learned that today's tires are also far superior to tires from back in the day. You get superior load handling, traction, tread life, etc, etc, etc,..... So today's trucks can run on strong comfortable quiet all season highway tires while under heavy load. There is simply no need for LT tires on 99% of the trucks we are using to pull our trailers. In most cases we lose more than we gain by going from a good P metric to the best LT tire.
Thanks for stretching me. I'm still willing to learn.
__________________
The Morgans
1989 Avion 34VB
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04-29-2017, 09:54 AM
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#20
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Rivet Master
1988 25' Excella
1987 32' Excella
Knoxville
, Tennessee
Join Date: Oct 2010
Posts: 5,095
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And I think that you well know that 1/2 ton or 3/4 ton is just a common parlance for a class of truck (yes, from the 80's) and does not tell what it will carry. I am not knocking your rig. But I think a Tundra is a 1/2 ton truck even if it will carry a small house, since you asked. And I know several people who pull Airstreams with them and love them for that.
I have had both LT and PXL tires in the Michelin LTX series and they seemed to be constructed very similarly. The load rating is slightly lower for the tires marked LT. I would be willing to bet they are almost the same tire but go through a different rating system.
I may have you miss-identified. Are you the same gentleman that ran a moving company with 500 tires on the ground at any one time and a fleet of pickup trucks? If not, then I apologize for my comment about "having fun with us".
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