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Old 12-18-2012, 01:02 AM   #1
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XL or C tires?

I was looking at tire options on Tire Rack and found something interesting,

The tires I was looking at were available in both C and XL weight rating in 235/75R15 size.

The C Tire is rated at 1985lbs
The XL tire is rated at 2183lbs

I read somewhere that XL is the rating for Car tires and C is the rating for truck tires. I checked and my Tundra has XL tires, they were recomended by the tire store when I bought them.

There is a slight cost difference with the XL tires being cheaper by about 25 a tire.

Is there any significant difference between XL and C rated tires? Either would have adequate carrying capacity for my light trailer.
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Old 12-18-2012, 04:29 AM   #2
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There is a significant difference between Load Range C tires and XL tires.

First, P type tires come in Standard Load (SL) and Extra Load (XL). When used in a light truck application (which includes trailer), P type tires have to be derated by a factor of 1.1.

So the ACTUAL load carrying capacity of a P235/75R15 XL is 1985# - and that occurs at 41 psi.

LT tires come in Load Ranges (A, B, C, etc). They are built sort of like their heavier duty brothers the over-the-road truck tires and they don't like flexing, so they use more inflation pressure (but they carry more load).

So an LT235/75R15 Load Range C has the same load carrying capacity as its little bortheer the P metric tire (1985#), but that occurs at 50 psi.
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Old 12-18-2012, 07:01 AM   #3
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Quote:
Originally Posted by CapriRacer View Post
There is a significant difference between Load Range C tires and XL tires.

First, P type tires come in Standard Load (SL) and Extra Load (XL). When used in a light truck application (which includes trailer), P type tires have to be derated by a factor of 1.1.

So the ACTUAL load carrying capacity of a P235/75R15 XL is 1985# - and that occurs at 41 psi.

LT tires come in Load Ranges (A, B, C, etc). They are built sort of like their heavier duty brothers the over-the-road truck tires and they don't like flexing, so they use more inflation pressure (but they carry more load).

So an LT235/75R15 Load Range C has the same load carrying capacity as its little bortheer the P metric tire (1985#), but that occurs at 50 psi.

Thanks,
So both tires have the same capacity, just at different PSI,

Is there an advantage to one over the other on a smaller trailer like my Safari at around 5000lbs?
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Old 12-18-2012, 09:31 AM   #4
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For trailers you need either LT or ST (in load range C or D) tires. The P indicates passenger vehicle. The ST is designed for trailers. There are differences. Lots of discussion on the forum over the years as to pros and cons of ST vs LT tires. Many people had failures with Goodyear Marathons, and other ST tires, and lots of people changed out tire and rims for 16 inch LT's. Search the forums if you have time and then make up your mind but I would not put a P rated tire on an Airstream.
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Old 12-18-2012, 10:13 AM   #5
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Kindly look at the sidewall of the Michelin LTX (P) 235/75R15 XL and it says in molded letters that the maximum load weight is 2,183 pounds at the maximum pressure of 50 psi. Derating the tire per 49 CVFR 5781.110 S4.2.2.2 by dividing 2,183 by 1.1 gives a payload of 1,985 pounds at 50 psi. The derating did not lower the tire pressure to carry the load.

The actual load on the axle of a 5,000 GVW trailer is not the 5,000 pounds GVW as the TV has at least 10% or 500 pounds on the hitch to tow properly and the percentage on the TV could be higher, thus the need to weigh the trailer using the old tires. Then an informed decision can be reached.

You would need to get a relatively accurate tongue weight when loaded for the road to determine how much of that weight could be transferred to the TV when using a weight distributing hitch system. Then cross a set of scales loaded (full of water + "your stuff") and see the load on the trailer axle. That is the actual weight the tires will be carrying at that instant.

Some folks on this forum decided to use the Michelin LT 225/75R16 E tire that Airstream used as the standard tire on the Eddie Bauer model and is offered as an option on most other models.
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Old 12-18-2012, 12:32 PM   #6
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This is getting even more confusing.

I've read many posts on tires and thought I knew what I was doing until I actually looked at tires.

The Michelin LTX in 235/75R15 is rated as and XL which seems to indicate it is a "P" tire, but the max load rating is 2183lbs at 50psi, which sounds like a LT tire. Is this an LT or P tire?



I appreciate all the posters suggesting I move to a 16" rim, and I understand the benefits, but I'm not considering that. My 23ft Safari is not nearly heavy enough to justify moving to a larger rim/tire. 15" tires in almost any configuration will have enough capacity to carry my trailer, I just need to decide which 15" tires to buy.

Consequently the tires currently on the trailer have a max inflation of 41psi, and neither myself or the PO who installed them had a problem, I'm only replacing them because of age.
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Old 12-18-2012, 01:27 PM   #7
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I'm sorry guys, but according the The Tire and Rim Association - the US tire standardizing organization, XL tires increase in load carrying capacity as the pressure goes up - to a maximum of 41 psi. This is the same for ALL tire manufacturers - not just Michelin.

I should also point out that it is permissible to use up to 50 psi for an XL tire - and that is what Michelin is marking on the sidewall.

I wish Michelin had a load table for this size - but they don't - but here's a link to what Tire Rack says about Standard Load and Extra Load tires:

Tire Tech Information - Tire Specs Explained: Maximum Load

Please note the table.

I would also point out that perhaps you have misinterpreted what is imprinted on the sidewall. If it says: Max Load XXXX at YY psi, then that is a relationship. But if it says Max Load XXXX, Max Pressure YY, then that is NOT a relationship.

Unfortunately, I have seen some tires that are marked - oh, let's say "not accurate" - and they use the "@" instead of indicating this is the maximum. While not technically wrong, it is misleading.

Now I am NOT at the particular tire in question, but I did look at a Michelin P metric tire and verified they are marking the tire I looked at accurately - indicating a max load and a max pressure and NOT indicating those 2 items are related.

So if you would do me a favor, please look at the particular tire in question and tell us what it says. I am hoping Michelin labeled that one accurately. If not, then I will shut up and not argue the point.
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Old 12-18-2012, 02:14 PM   #8
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My Michelin LTX M/S2 P 235/75/15 XL are stamped with the following:

CANADA AND U.S. CODES ONLY
MAX LOAD 990 KG (2183 LBS)
MAX PRESS 340 kPa (50 PSI)
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Old 12-18-2012, 02:20 PM   #9
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Our LTX's are @.....or more accurately at.

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Old 12-18-2012, 02:33 PM   #10
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If his trailer is only 5000 lb he will have plenty of margin with an XL rated tire. My 31 footer GVW is 7000lb and I still have plenty of margin. The derating of the XL tires to 1985 lb only applies to high profile high CG vehicles like SUV's. An Airstream trailer has a low CG close to that of cars. Still there is almost a factor of 2 safety margin no matter how you argue. I am running 235/75-15 XL BF Goodrich Tires and have had no issues. They run cool as cucumbers at 70 MPH.

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Old 12-18-2012, 02:35 PM   #11
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Sorry I don't have a Michelin tire to look at, I'm tryin to decide based on Tirerack and Michelin websites which 15" tire I should buy.

I was trying to understand why one tire is "better" but I think I just stirred thing up.

To make this simple on myself here's the question:

Should I buy

A) Yokohama Geolander HT-S G051 LT235/75R15 - Load rating: C

or

B) Yokohama Geolander HT-S G051 P235/75R15 - Load rating: XL
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Old 12-18-2012, 04:06 PM   #12
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As I understand from reading the many tire threads here on the forum, the "LT" tire would be the better option due to stiffer sidewall and heavier construction. This in turn should lead to a lower chance of blowout.
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Old 12-18-2012, 04:41 PM   #13
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I think the stiffer sidewall falls into the urban myth catagory. It sounds like those tires are exactly the same tire under the lable. Flip a coin. I am not convinced that a stiffer sidewall means anything. A tire with 80 psi in it will have a stiffer sidewall than one with 50 psi in it. Stiffer sidewall also means more vibration transmitted to your trailer. We have heard many accounts of blown bias ply ST tires and none that I know of with passenger rated tires. Anything that is rated not to kill people is going to be less prone to blowing out and have a higher speed rating than trailer tires.

I bet the number of plies is the same on both tires.

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Old 12-18-2012, 05:21 PM   #14
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Quote:
Originally Posted by AldeanFan View Post

A) Yokohama Geolander HT-S G051 LT235/75R15 - Load rating: C

or

B) Yokohama Geolander HT-S G051 P235/75R15 - Load rating: XL
According to Tire Rack both tires have the weight at 34LBs each so there can't be much difference.
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