How heavy a trailer to justify G rated tires.

[John303]

I am planning to put the Morryde IS and disc brakes on my 303RLS in May (12,000 GVW). I currently have the 15" wheels/tires from the factory. I plan to use a 16x6.6 8x6.5 rim rated at 3640 lbs. G rated tires (ST235/80R16) seem to run about 4100 lbs capacity vs 3500 lbs for the same size but load range E. Even using load range E tires would give me a large weight cushion. So my question for the community is when does it make sense to go to G rated tires; i.e. how heavy a load to really justify the expense?

Thanks.

[howson]

I am planning to put the Morryde IS and disc brakes on my 303RLS in May (12,000 GVW). I currently have the 15" wheels/tires from the factory. I plan to use a 16x6.6 8x6.5 rim rated at 3640 lbs. G rated tires (ST235/80R16) seem to run about 4100 lbs capacity vs 3500 lbs for the same size but load range E. Even using load range E tires would give me a large weight cushion. So my question for the community is when does it make sense to go to G rated tires; i.e. how heavy a load to really justify the expense?

Thanks.

What does Morryde recommend? I ask based on my perception that G rated tires will be stiffer thus transferring more of the suspension work to their IS.

Two things do come to mind, though, for the extra load capacity. 1) Should you have a tire failure, the remaining tire on that side of the tandem has extra capacity to absorb the weight. 2) It is amazing (to me) how quickly a tire's load capacity drops when tire pressure is less than maximum. Having the extra capacity in the "G" can absorb some loss of pressure yet retain full capability of carrying your 303's weight.

All I wrote above can be confirmed at https://www.tirerack.com/tires/tiret...jsp?techid=309. Here's another gem:If drivers are considering upgrading their tires to a heavier load range that allows higher inflation pressures or larger-sized tires, wheel suitability must be checked, fender clearances confirmed and frame strength verified. Hitch adjustment may also be necessary if the replacement tire is larger in diameter than the original.

Please follow-up with what you do (and why).

Edit: Just to be clear--I am not advocating for the G rated tires. I have no personal experience or expertise on ST tires other than what I've learned here on this forum and through extensive reading.

[Rapid1]

My 303 weighs in at 11250lbs., 8800lbs of which is on the tires. Load range G tires are nearly double the weight needed. Many will argue that you can air them down but still seems to be much more tire than needed for a 303. There are some great choices for E tires that are mentioned in several threads here that would be more suitable for the loads carried with a 303.

[warsw1]

I would go with the "E" rated tires. They would be more than enough tire for your 303. With the "E" rated tires you will have way more choices of some really good tires and get better prices. "G" rated tires would be over kill IMHO.

That being said....If you do a lot of off road travel with your trailer the extra ply rating of a "G" rated tire might be worth it.

[John303]

Thing is, a Goodyear Endurance E rated tire is about the same price as a Sailun G rated tire. If you inflate to the load, why not go with the G rating?

[Leon T]

My experience with using higher rated tires on vehicles has always been that the ride suffers tremendously. Had a 2009 Ford F-150 and thought it would be a great idea to swap out the factory tires for D-rated BF Goodrich TAs. Horrible decision. Went from riding like a Cadillac to one of the worst rides ever. First time my wife rode in it after I got the new tires she just gave me that look like WTH did you do to the truck? Same with patrol cars. Our boss once decided it would be a great idea to put heavy rated tires on our SUVs to cut down on tire punctures. It was not good. Those SUVs literally beat the crap out of us after that.

My reason for posting this is that I'm sure heavier rated tires are going to do the same thing to your trailer. You just aren't riding in it to be able to see the difference. I'd stick with the E rated tires.

[John303]

The responses here have spurred further searching, and I ran across this post at RVSAFETY... https://rvsafety.com/articles/writte...lation-ratings . Here is the part that caught my eye...

Note: Towable – Travel Trailer/ 5th Wheel owners Due to the sever use conditions experienced by tires when axles are very close together – tire industry experts recommend maximum (sidewall) inflation pressure for towable tires unless this causes a sever over-inflation situation (20psi+), often referred to as the ‘basketball effect’. If this is your situation allow a 10 – 15psi safety margin above the minimum required inflation pressure.

...this makes complete sense to me. What I take from this is to use a tire's inflation chart to match load and psi; then add 10-15 lbs, but do not exceed the sidewall rating. All this predicated on knowing what weight is on the tire, which I do, having had it weighed at the rally a few months ago. So using Sailun's chart as an example, and working with a tire weight of 2600lbs, I get 50 psi. Adding 15 lbs takes me up to 65 psi. I think this will give me the benefits of a G rated tire, but avoid the problems of an overinflated tire's impact and wear to the trailer. The Morryde IS comes with shocks also, so that would be added control.

Is there a flaw in my thinking?

[Country Campers]

John303
I had my camper weighed at the Indiana Rally and they said I could drop my tire pressures down to 45-40 psi, the tire chart shows this to be a safe operating pressure to handle the weight on each tire of my camper. I could only imagine the effects of traveling on tires that were inflated to only have of the pressure recommended on the side wall. I chose not to follow there recommendation. On trailer tires I have always been told to inflate to side wall recommended pressure. My 16" tires are set at 80 psi.
Just my opinion.

Brian

[howson]

The responses here have spurred further searching, and I ran across this post at RVSAFETY... https://rvsafety.com/articles/writte...lation-ratings . Here is the part that caught my eye...

Note: Towable – Travel Trailer/ 5th Wheel owners Due to the sever use conditions experienced by tires when axles are very close together – tire industry experts recommend maximum (sidewall) inflation pressure for towable tires unless this causes a sever over-inflation situation (20psi+), often referred to as the ‘basketball effect’. If this is your situation allow a 10 – 15psi safety margin above the minimum required inflation pressure.

...this makes complete sense to me. What I take from this is to use a tire's inflation chart to match load and psi; then add 10-15 lbs, but do not exceed the sidewall rating. All this predicated on knowing what weight is on the tire, which I do, having had it weighed at the rally a few months ago. So using Sailun's chart as an example, and working with a tire weight of 2600lbs, I get 50 psi. Adding 15 lbs takes me up to 65 psi. I think this will give me the benefits of a G rated tire, but avoid the problems of an overinflated tire's impact and wear to the trailer. The Morryde IS comes with shocks also, so that would be added control.

Is there a flaw in my thinking?

From http://www.rvtiresafety.net/search/l...lation%20table ...RV tire inflation is different. Due to SIDE LOADING in trailer application, I strongly recommend running the tire sidewall inflation as your CIP {CIP=cold inflation pressure}. I think that if you review the RV Placard info from the RV company you will also find that they say to use the inflation number on the tire sidewall.

From https://www.etrailer.com/question-78836.html I can end this debate for you real fast! Trailer tires, which will have an ST in front of the size, should always be inflated to the maximum psi indicated on the tire. Trailer tires usually do not have a recommended and maximum psi indication so I am curious if the {tires} on the camper are ST tires or regular passenger vehicle tires. On a regular trailer tire you would inflate it to the max psi indicated on the tire because trailer tires are built with a thicker sidewall to handle more vertical load.

If a trailer tire is under inflated, because of the thicker sidewall it will generate excessive heat and that is what leads to failure.

Check the camper frame and there should be a sticker or plate that lists what tire size should be on the trailer. It could also be in the owners literature. That is the size you will want to stick with...

[Bamaman]

We use Bridgestone Duravis R250 E rated ribbed tires on our 323BHS. They're extremely stiff, thick and heavy tires and all my 11k dry weight trailer requires. I would consider going G rated tires on a Momentum fifth wheel trailer. Our tires were $200 each--far cheaper than the G614 Goodyears and there are dealers everywhere to service them.