G or H rated tires on Ford F53 18,000 Chassis

[Agility57]

Originally Posted by jadatis

As long as you keep these tires, let me calculate a safe highest pressure, at wich comfort and gripp is still acceptable.
Then first comfirm the data .
Front GAWR 7000 LBS
Rear GAWR 12000 lbs dual load.
Tires 245/70 R 19.5 H-load.
Weighing fully loaded , as you go on trip might prove that front is overloaded, best would be to weigh per axle-end.
Correct these data please.
What pressures did you use upto now?

Reading back, I see TM9 already advising weighing.

I corrected myself earlier on, my data placard shows 20,000 GAWR total. I cannot remember the specifics front and back.

I have been running 90 PSI in the front H tires. I cannot imagine I have come anywhere near overloading the fronts at any time.


I find some scales and reweigh.

[FredV]

The tire placard that is located somewhere inside the Motorhome, on my 2000 f 53 near the drivers seat, specifies what load range tires to use. I wouldn't deviate from the specified load range except to go higher.

[Bytesponge]

Originally Posted by Agility57

What are most of you running on your Ford 18,000# chassis from a tire rating perspective? I have H rated steer tires that need to be replaced and often wonder if I should go to a G rated tire for a more forgiving ride. In addition to a softer ride there would be less weight per tire, it all adds up. Plus, I have never been able to get these tires to run smoothly from a balance perspective, which makes me wonder about the extra heavy tire on this chassis.
Thoughts?

Running Good Years G-Rated on an F53 Ford 18,000 lb rig. Forest River FW30 classA 30 footer.

[NeilV]

Originally Posted by HarryStone

I don't understand at all????
The letter designates the tire speed rating, with truck tires being rated for an L? correct?
The number rating designates its load carrying capacity, whereas the load range letter just identifies how many plies the tire has.
https://rvtires.com/tire-load-capacity/?v=7516fd43adaa

Letter ordinal position in the alphabet times 2 equals ply rating on the load range specification.

Load range B is a 4 ply tire while load range C = 6, D = 8, E = 10, F = 12, G = 14 and H = 16 ply.

Temperature and traction ratings also go by A/B/C.

I go by the tire placard with the exception of bumping all tires to the highest load rating if one axle takes one step lower in load rating even though its the same size as on the other axle which is the case on the F53 with the 19.5 inch rims. My coach has a spare so that keeps all 7 tires the same and basically universal. If you travel extensively in the Deep South then you may want to consider bumping up the load rating one above the highest listed on the tire placard to better deal with the heat so if it lists F as the highest rated tire required then bump them all to G and if G is the highest listed bump them all to H.

Remember that Motor Home tires at MAX only have a 75 mph speed rating and most are only tested for an hour or less at the MAX rated speed with many only tested for just 10 to 15 minutes at moderate temperatures.

[jadatis]

Originally Posted by Agility57

I corrected myself earlier on, my data placard shows 20,000 GAWR total. I cannot remember the specifics front and back.

I have been running 90 PSI in the front H tires. I cannot imagine I have come anywhere near overloading the fronts at any time.


I find some scales and reweigh.

Then I assumed ( oooh dangerous) next
Front 8000 lbs needs 110 psi, and rear 14000 lbs needs 101 psi.

Used 135/133 loadindex AT 120 psi, found in a TOYO list.

Where you the one that noticed both sidewear on front tires? Then the 90 psi gave to much deflection so heatproduction, and savety of tire now is questionable. Could even be that if you pump it up to 110 psi, the tire will blow.

When you weighed, I can calculate saver.

[Tireman9]

Originally Posted by Agility57

Quite a bit, 5 Irish Setters/ myself, DW, and all the gear for the show dogs. I weighed at a truck stop once and got just around 17,500 if I remember correctly, but that was not fully loaded.

Data from over 10,000 RVs being weighed by position, not just by axle or total, indicates that a majority (more than half) of RVs have an axle or tire or both in overload.
Almost no RVs have perfect 50/50 side to side load split. Some large MH have been found to be 1,000# out of balance.
Until you can learn the facts of the weight of your RV I suggest.
1. At a minimum get the individual axle weight when the coach is at it's heaviest
2. Assume you have a side to side load split of 53/47 for any RV with a slide or residential refrigerator or if your generator and fresh water tank are on the same side. If no slides or the above placement then you can go 51/49% Use these estimate load split for each axle

3. Using the heavy end weight in #2 check tire company Load & Inflation tables to learn the MINIMUM inflation to run for each axle. I recommend you add 10% to that minimum inflation number. Inflate all tires on an axle to the same level.

4 Set the TPMS low Pressure warning level to the inflation in #2 minus a couple psi. Set or leave TPMS High Temp to 158F which is the factory setting for most TPMS. You can set the high pressure warning level to the inflation in #3 plus 25%.
5 Go and enjoy your RV

[Randalpho]

Originally Posted by Tireman9

You need to be careful about switching lug nuts. Some wheels are "Hub-centric" while others are "Lug-centric". The hub center ledge that the wheel "centers on" may or may not be machined to center the wheel.


If the hub is machined and the wheel also machined as hub-centric and you use some lug centering nuts you can mess up the machining of the aluminum wheel.

I'm not saying to replace all the lug nuts. I'm saying I use 3 tapered lug nuts on the Ford factory steel rims to center the wheel temporarily while installing the factory lug nuts. Much like the wheel centering adapters that were suggested earlier.

I did forget to mention that I literally hand tighten (without any tools) these 3 tapered lug nuts while using them as centering tools. I do need to jockey the wheel slightly to get all 3 started and snug. If I was removing the wheels more often I probably would buy the tool.

[Ryqster]

G's are plenty enough tire IMHO. Plus you are more likely to find these in a highway compatible speed rating. Not that that is what you should use to set your internal speed/wisdom meter.

[2upServant]

I also use balancing beads. I started using them in my motorcycle tires and found that it really helped with cupping and ride stability. I started using them in my Freightliner with 22.5 inch tires and the wear pattern is really even. reduces the vibration substantially. I also agree with the poster about making sure the wheels are centered on the lugs. if you are running a hub piloted wheel that helps. have you checked to make sure the wheels are not off center some how. check to see if the wheel is spinning straight.

[TeJay]

NeilV,

Below you see what is stamped on my TOYO tire sidewall:

Load Range is rated at "H" 4940 single tire That's at max pressure!!

Load Range 4675 Dual tires.

Tread is 5 ply & steel. Good puncture protection with 5 steel treads.

Sidewall is 1 ply & steel. Maybe this is why they ride smoother with only 1 steel side wall.

Am I missing something since your Load Rating info does is not the same as mine. There's not enough plys to be rated an "H" tire??? That said!!! So far it's a really great tire that rides much smoother than the stock GY RV tire.

[Tireman9]

Originally Posted by TeJay

NeilV,

Below you see what is stamped on my TOYO tire sidewall:

Load Range is rated at "H" 4940 single tire That's at max pressure!!

Load Range 4675 Dual tires.

Tread is 5 ply & steel. Good puncture protection with 5 steel treads.

Sidewall is 1 ply & steel. Maybe this is why they ride smoother with only 1 steel side wall.

Am I missing something since your Load Rating info does is not the same as mine. There's not enough plys to be rated an "H" tire??? That said!!! So far it's a really great tire that rides much smoother than the stock GY RV tire.

The number of 'Ply" or layers of cord (textile or steel) are not in themselves any proof of strength. Individual cords of steel are made up of many strands. The steel or material used to make the strands can have a wide range of strength. Also the number of strands and even the "twist" of the strands can affect the strength and flexibility in the end product.


There are a number of different tests conducted on tires to establish their "strength" rating and the different materials can help a tire meet the different tests. It is completely possible for a given tire to pass some tests associated with a given level. Lets say "G". BUT if a given tire only passes the "F" level then the tire would be rated as "F".
Now if the sales dept wanted a "G" rated tire then they would ask the engineer to change the specification so the tire could pass all the "G" level testing. This change or "improvement" may or may not result in more layers of steel. I can relate to an actual example of such a process in a tire I developed. It turned out in this case that the only change I needed to make was the wire in the "Bead" of the tire. This is the "cable" of wire that holds the tire on the wheel. it is kind of an anchor for the body ply.

[TeJay]

Tireman9,

Thanks for your responses. I don't believe we have ever had a tire engineer on these forums. You live in Akron, OH probably close to your place of work also.

I was born in PA, and we lived in IN and MI so traveled through OH many, many times.

I am kind of familiar how tires are constructed. I showed movies on how tires were made to all my beginning classes. That was before Radial tires but I'm sure the process was similar in many/some respects.

So I guess our TOYO tires are only 2 and 5 ply but still pass for a G rated tire.

[Agility57]

Originally Posted by 2upServant

I also use balancing beads. I started using them in my motorcycle tires and found that it really helped with cupping and ride stability. I started using them in my Freightliner with 22.5 inch tires and the wear pattern is really even. reduces the vibration substantially. I also agree with the poster about making sure the wheels are centered on the lugs. if you are running a hub piloted wheel that helps. have you checked to make sure the wheels are not off center some how. check to see if the wheel is spinning straight.

I checked the hubs for centering and I think they are OK. Mine is a 2004 which was not listed in an earlier post as being in the years with the hub centering issue.
I measured no more than .004 with my feeler gauge between the hub tabs and the rim on the fronts, .005 on the outside rears. Not sure how there could be any less or it would be darn near impossible to mount the tire assembly to the rig.
I might try balancing beads in the fronts when I do get tires this time. I have the Centramatics on the rears now. Still have the out of balance sensation at 60 MPH. I wish I can find a tire installer that is very familiar with and has worked with these 19.5 setups that I can trust. I have been to two different truck tire shops in my area (Columbus Oh) and the out of balance or out of round issue persists.

[Tireman9]

Many times what people thnk is an out of balance situation the real problem is out of round.
I have covered this a couple of times in my blog. I even showed how I "balanced" a cement block.
19.5 & 22.5 are also more likely to be mounted out of round because of the taper fit between tire and wheel. Even improper lube or inflation standing up can result in out of round condition.