Load rating of new tires

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Load rating of new tires

May 07, 2019, 10:47:18 pm

I plan to get some new tires for our coach. The front tires (Michelin X-line Energy, load rating G) were new last year. I planned to move these two to the back and buy two more G rated Michelins for the back to match them as closely as possible. And buy two H rated tires for the front.

But one of the dealers here in Tucson thought that was a bad idea and that I should buy four H rated tires. That way one side in back would be H and the other side G rated. He thought having 4 H rated tires would allow me to rotate the four tires and get better wear. I really didn't like this idea because I would have two different pressures on the back tires.

What do you think of his idea? And does it sound OK to go with H rated tires in front and G rated tires in back.

Thanks in advance for any advice.

Re: Load rating of new tires

Reply #1 – May 07, 2019, 11:40:53 pm

Gs in the rear, Hs on the front are just fine. As far as rotating is concerned, unless your rear wheels are polished on both sides the tires would have to be remounted. IMHO not worth it.

Re: Load rating of new tires

Reply #2 – May 08, 2019, 08:07:55 am

It is probably OK but as soon as you have 4 Gs in the rear you are stuck with them. If you are thinking in six years replace then with Hs what happens if you have a tire problem between now and then? You can't replace it with an H. Find a buyer for the Gs, get 6 Hs.

Every three years I buy 2 or 4 tires. Spread out the cost. And I always have front steer tires that are no more than three years old.

Re: Load rating of new tires

Reply #3 – May 08, 2019, 08:59:25 am

Rotate? we never get enough miles on our coaches to worry about rotating. Your G's on the back and new H's on the front are the way to go.

Re: Load rating of new tires

Reply #4 – May 08, 2019, 09:24:07 am

They will age out before you need to worry about rotating them. I personally would not want to combine a G and H rated tire on the same dual. Not sure if you would run the same pressure in both or inflate to the proper pressure per the manufacture chart for each rating.

All G rated on the rear or as suggested .... all six H rated.

Re: Load rating of new tires

Reply #5 – May 08, 2019, 10:09:09 am

I never rotate RV tires. They age out before they wear out. H in front and G in back should be fine if you have checked the load ratings and with proper inflation.

Long term goal should probably be H all the way around - but front axle is the critical one.

Re: Load rating of new tires

Reply #6 – May 08, 2019, 10:13:57 am

Why do you need H rated? It will ride rougher.

Re: Load rating of new tires

Reply #7 – May 08, 2019, 11:33:11 am

We switched from LRG to LRH and think the ride improved noticeably. Much better cross wind stability. LRG will not be sufficient to carry maximum axle loads especially in the front. The only way to know which tires to use is to weight the coach in its normal in-use state.

Re: Load rating of new tires

Reply #8 – May 08, 2019, 11:59:31 am

George with all the 1st class upgrades you are making to your new coach, buy LR-H. Ask no more. You will not be sorry or have future regrets. What tire dealer are you going to use.

Re: Load rating of new tires

Reply #9 – May 08, 2019, 12:13:01 pm

Obviously it depends on the RV. My 34' 270 is pretty light. I'm not even close to capacity of the G's.

Re: Load rating of new tires

Reply #10 – May 08, 2019, 12:18:37 pm

Thanks, everyone.

Barry, I'm thinking about using Redburn Tire of Tucson. The estimate I got was the lowest of the two I checked and the person I talked to actually listened to what I wanted (two G and two H). Both quoted FMCA prices, but Redburn had slightly lower labor costs.
We had this setup on our '03 and it worked well. Same deal... when we bought that U295 coach it also had G load rating tires on it. So I traded in the two fronts on H rating tires and had no problems.

Re: Load rating of new tires

Reply #11 – May 08, 2019, 12:29:35 pm

Quote from: George Hatfield – May 08, 2019, 12:18:37 pm

Thanks, everyone.

Barry, I'm thinking about using Redburn Tire of Tucson. The estimate I got was the lowest of the two I checked and the person I talked to actually listened to what I wanted (two G and two H). Both quoted FMCA prices, but Redburn had slightly lower labor costs.
We had this setup on our '03 and it worked well. Same deal... when we bought that U295 coach it also had G load rating tires on it. So I traded in the two fronts on H rating tires and had no problems.

If you go with the 2 new G's have them mounted on the same side in the rear. Otherwise the diameter difference causes tire wear. There is no issue on the differential doing this. I have always bought my tires in pairs on the crane as it gave me the most bang for the buck. I did wear tires out before aging.

Re: Load rating of new tires

Reply #12 – May 08, 2019, 12:38:05 pm

Redburn is a quality act, they did our Michelins in Phoenix. They 'force balanced' ours.

Re: Load rating of new tires

Reply #13 – May 08, 2019, 12:53:09 pm

Roger in Reply #7 you said:
"We switched from LRG to LRH and think the ride improved noticeably. Much better cross wind stability."
This really surprises me!
What brand of tires did you replace, what brand of tires did you buy, and what pressures are running?

Roger in Reply #7 you said:
"LRG will not be sufficient to carry maximum axle loads especially in the front."
I do not believe this statement! It indicates that Foretravel put undersized tires on George's 2000 U295 which has a GVWR of 33,000 pounds. My 1996 U320 has a GVWR of 32,000 and the tire pressure placard beside the driver seat indicates 97psi front, 90psi rear, while the maximum pressure for "G" rated tires is 110psi, so "G" tires on the front of my U320 could carry 12% more load than they do. This does not seem like overload to me.
The reason I have resisted replacing my "G" tires with "H" tires is the firmer ride that other folks have reported with "H" tires.
Now you indicate a softer ride with "H" tires which I am very interested in.
I considered replacing my 275 80 tires with 305 70 Michelin XRV tires but there are very few 305 70 tires in the market so finding an emergency replacement could be impossible.

Re: Load rating of new tires

Reply #14 – May 08, 2019, 12:57:49 pm

Quote from: P. Wyatt Sabourin – May 08, 2019, 12:53:09 pm

I considered replacing my 275 80 tires with 305 70 Michelin XRV tires.

I would also be concerned about the much wider tires interfering with body and suspension components like the drag link (or really negatively affecting cut angle).

Re: Load rating of new tires

Reply #15 – May 08, 2019, 01:13:55 pm

I use different tires on each axle Steer tires on the front and drive tires on the rear, So long as you are within the load rating of the tire stay with it. Rotating tires is not needed with the low miles we put on our coaches. Do not mix load ratings on the same axle.

Keith

Re: Load rating of new tires

Reply #16 – May 08, 2019, 01:42:54 pm

Likely quite the opposite when it comes to "Why do you need H rated? It will ride rougher"

LR-H can carry more weight and PSI, which means when you put in the correct PSI for the weight of the coach, we will not be pushing tire to max capacity.

Also loads on a tire from our 30,000 + vehicles are not just scale weight. Consider side wind, PSI lower than optimum at any time due to higher altitude, cold temp, leakage, etc... Always allow for a safety margin

LR-G may be ok, but don't assume there are disadvantages to LR-H other than cost.

Re: Load rating of new tires

Reply #17 – May 09, 2019, 01:04:56 am

Minus 10 psi all around going from g to h greatly increased the ride quality on square edged bumps.

Re: Load rating of new tires

Reply #18 – May 09, 2019, 01:32:45 am

Bottom line IF LR G are sufficient to carry the actual load they will perform just fine properly inflated. LR H will carry the same load at a lower pressure. 99% of folks won't be able to tell the difference. As far as brand is concerned, blindfolded I'll bet one in ten could tell the difference in one brand or the other. Sorry for the rant, I'm done. In the end as always DWMYFG.

Re: Load rating of new tires

Reply #19 – May 09, 2019, 07:41:00 am

Wyatt. The maximum load for the LRG tires that we on our coach was less that the GAWR for the front. We were weighed at under the front GAWR but very close to the max load of the G tires on one side. Plenty of weight room in the rear. So we switched to LRH. As I said ride and handling improved especially in windy conditions.

Michelin LRG tires at 110 psi carry 6175 each or 12,350. Front axle weight rating in my coach is 13,880 as I reacall. LRH at 120 psi carry 7,160. At 100 psi they carry 6190.

I have no idea who put what or why or at what pressure on George's coach or what his GAWRs are. My guess is the LRG tires are undersized tires as far as GAWR and maybe inflated about as needed for an empty coach to feel good.

I know my coach is not over weight on any corner and I know my LRH tires can carry the weight. Good enough for me. Everyone else gets to do what they want, please don't have a blow out in front of me.

Re: Load rating of new tires

Reply #20 – May 09, 2019, 07:50:58 am

Quote from: Roger & Susan in Home2 – May 09, 2019, 07:41:00 am

Wyatt. The maximum load for the LRG tires that we on our coach was less that the GAWR for the front. We were weighed at under the front GAWR but very close to the max load of the G tires on one side. Plenty of weight room in the rear. So we switched to LRH. As I said ride and handling improved especially in windy conditions.

Michelin LRG tires at 110 psi carry 6175 each or 12,350. Front axle weight rating in my coach is 12,880 as I reacall. LRH at 120 psi carry 7,160. At 100 psi they carry 6190.

I have no idea who put what or why or at what pressure on George's coach or what his GAWRs are. My guess is the LRG tires are undersized tires as far as GAWR and maybe inflated about as needed for an empty coach to feel good.

I know my coach is not over weight on any corner and I know my LRH tires can carry the weight. Good enough for me. Everyone else gets to do what they want, please don't have a blow out in front of me.

The front axle is 13,880 and the rear 21,000

Re: Load rating of new tires

Reply #21 – May 09, 2019, 09:22:28 am

"As far as brand is concerned, blindfolded I'll bet one in ten could tell the difference in one brand or the other. "

My real world experience says otherwise. I felt an immediate degradation in steering when I switched from Michelin to Continental. In the first 10 miles I knew I preferred the Michelin steering by FAR.

Now on tag and drive I expect it would be true to be hard to tell the difference. On steer axle the difference was immediately and dramatically noticeable. So much so that I will be changing back to Michelin on steer within the next year. (they were installed Mar 2018)

Re: Load rating of new tires

Reply #22 – May 09, 2019, 09:36:54 am

A number of factors here:

Old (more cross-links/stiffer) vs new (more pliable rubber)

Tires not yet "broken in". Handling, particularly during the first few hundred miles is more "squirrely"

Tread pattern and tread depth differences

Re: Load rating of new tires

Reply #23 – May 09, 2019, 09:50:58 am

Also a decrease in fuel economy with new tires for several thousand miles if both sets are the newer lower rolling resistance types.

"New, Full-Treaded Tires Generate More Rolling Resistance Than Shallow-Treaded, Worn Tires. ... Since the automotive industry estimates a 10% increase in tire rolling resistance will result in a 1% to 2% decrease in vehicle fuel economy, drivers should expect to experience a potential 2% to 4% decrease in mpg."

Pierce

Re: Load rating of new tires

Reply #24 – May 09, 2019, 09:54:53 am

Quote from: Roger & Susan in Home2 – May 09, 2019, 07:41:00 am

Michelin LRG tires at 110 psi carry 6175 each or 12,350. Front axle weight rating in my coach is 12,880 as I reacall. LRH at 120 psi carry 7,160. At 100 psi they carry 6190.

The bolded info above has always not set well with me. The air supports the weight. How can the same size tire hold more weight at the same PSI? So I started doing some research and stumbled upon this guy's post (which I presume he is actually a tire engineer/expert).

Quote

Lets see if i can shed some light to help clear up the confusion.

Since the load is carried by the air and not the tire it is reasonable for tires to have the same load capacity at the same inflation, no matter the Load Range. You can read more at this site. rvtiresafety.com

I took a look at the Load/Inflation tables at Firestone pg 4 of 9 and find the LR-G tires are rated for 6175 Lbs @ 110 psi and LR-H 6610 Lbs @ 120 psi.

Goodyear page 15 we see the ratings 6175 @ 110 and 6610 @ 120 for the G and H Load Range.

Michelin tables for size 275/80R22.5 LR-G shows 6175 at 110 psi but LR-H shows 7160 Lbs @ 120 psi.

NOTE the different Load Range Michelin tires are also of different design so there are a number of possible reasons the 7160 Lbs is different for the other tires. This shows why it is important to check the Load/Inflation tables published by the manufacturer of your specific tires.

Industry Standards as published by Tire & Rim Association show a 295/75R22.5 and 275/70R22.5 as being rated the same at 6175 at 110 for LR-G and 6610 at 120 for LR-H. If a manufacturer makes some special provisions or design changes and tests to a different load they may choose to publish load capacity that is slightly different than you might find for a different design or from a different manufacturer.

To answer your final question, you can not simply change the Load Range but not change the inflation pressure and assume that you will have a different load capacity. You must use the tables from your tire manufacturer for your exact tire and be sure you always check your inflation and have enough air to carry the load. You did not say what your actual loads are I can't look at the possibility of there being a choice of a tire that would allow a lower inflation but I doubt the inflation difference would be very significant.

A Little Confused Over G vs H Rated Tires And Load/Inflation Data -- Updated...

EDIT: I suggest reading the FMCA thread I linked. Lots of interesting information.

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