ATF: MPG - Going from C range to D range Tires

[marc515]

I currently have a 2011 MPG with the Platnum Package. The MPG currently has 15" Towmax "C" rated tires.

I would like to go with the 15" loadrange "D" tires, and would like to know if the wheels are rated for the extra pressure?

EDIT: "C" range= 50 PSI; "D" range= 65 PSI

Thank you

 

[oldmannj]

you're gonna have to pull the wheel off the trailer to be sure. The rating is stamped on the back of the wheel. But I THINK all 6 lug 15" wheels are rated for 80 lbs. ED

 

[Tumblebug]

I had a MPG 183(2011) which had the 5 spoke, 5 lug, Vision Legend 5, gun metal machined lip 15" rims, I checked all the sources Heartland, Treadit(supplier to Heartland, and did not get a defined answer, so off to the tire store, got the range D tires and had no problem with the tire pressure, but I would not go to tires that require 110 LBs with those rims. Couldn't find anything on the rims. I towed them a couple of thousand miles and they worked well. They were Mastertrac tires. They were 205/75/15, range D. The lugs were torqued to 100 lbs. I found a range of 90 to 110 # torque. no one wants to give answers that may involve liability!

 

[Jadatis]

I registered to this forum to give information.
Once got hold of the formula, the European tyre-makers use to determine advice-pressures and went running with it.
Learned myself Excell to make spreadsheets for it , and translated a few from Dutch to English to go worldwide with it.
Now I frequently google for tire-pressure to see if I can give the information.
Wil not introduce myself in a seperate topic, because I dont have a camper or caravan anymore.
Excuse me for mis-spellings and strange words, in Holland we use some different terms, feel free to give the right words, and I will use them further on.

Now my reaction:
But why should you change , is the maximum load of your tires on the edges of what the tires together can bare, so they barely carry the GAWR ( gross axle weight rating).
If you C-load/6py tires have a comfortable reserve, I would not chance. The rear axle mostly goes to the edges.
D-load/8ply tires have a reference-pressure of 65 psi ( miswriting I think, your 60).

Reference-pressure ( further Pr also saw it written maxloadpressure) is not the maximum pressure.
From C-load tires you always see something like this on the sidewall "maximum load xxxx lbs AT yyy psi (cold)", P-tires and XL/Extraload/reinforced only give maximum pressure, the Pr is P-tires 35 psi for American tires, and 41 psi for XL on american tires.

I have concluded from an European list at wich 2 times the maximum load may be carried at 1,4 times the Pr when standing still, that the maximum pressure ( Pmax) is 1,4 times the Pr.
In Europe part of that extra is used on Campers ( another word that is different probably in America, RV?) with mostly D-load tires (C-tyres callled for Comercial, somewhat confusing).
They advice 5,5bar/80 psi instead of the 4,8bar/70psi Pr.
America has a stiffer system, D-load always is 65 psi/4,5 bar. But Special trailer tires ( ST) acording to tire-rack may be filled with 10 psi higher for higher speed then 65m/h.
So they come to 65+10=75psi wich the tire-makers support. Your valves must be Hi-pressure rubber valves at least then.
Metal valves always OK above 10 bar/140 psi.

But I dont know all the American terms like MPG, mayby it what we call a caravan in Holland.
If you finally have the new tires, I can calculate a save advice-pressure for them.
Give me GAWR's and exact maximum load and Pr , read from the sidewalls in mostly the notation mentioned above, and I will give advice pressure as example here.

 

[danemayer]

Hi Jadatis,

I registered to this forum to give information.

Welcome to the Heartland Owners Forum and thank you for contributing to the discussion.

 

[marc515]

Jatadis,.....thank you for your detailed post, but it was a little too in depth for my purposes; simply put- way over my head.

The only reason I want to go to "D" range tires is my simple mind tells me that an 8ply tire "D" range tire should provide me an extra margin of safety over a 6ply "C" range tire

 

[Jadatis]

But if you already have a comfortable reserve , you dont have to change.
For that you only have to read the data of the tires and vehicle, not so difficult I think.
Tires on the sidewall and vehicle on a metalisch plate somewhere .
In Europe it has to be on the vehicle and saw it called a Vin-plate.
But in America the GAWR's are mostly on the same plate as the pressure-advices.

The pressure rating of the tire, is another subject.
But if you change from C to D-load ( saw you changed the Pr to 65 ), You must know that for the same load the D-tire needs a higher pressure then the C-load.
And dont go looking in American lists from the tire makers, they come to lower pressures for the same load, or the other way around to high loadcapacity for the same pressure. Also C- and D-load are placed in the same list, and that is wrong. For every Pr and Lmax a different list has to be made.

 

[Tumblebug]

It is my understanding that the MPG has 205/75/15 Load range C, the trailer has a 3500 lb axle and the GVWR is 3800 Lbs, 3500 lbs on axle, 300 lbs hitch weight. The load range C at 50 PSI is rated at 1820 lbs per tire or 3640 combined, single axle trailer. The load range D, 205/75/15 tires at 65 lbs are rated at 2150 lbs, or 4300 lbs combined. That will give a margin for weight and more protection against most road harzards. The rims will handle the 15 lbs extra tire pressure.

 

[Jadatis]

It is my understanding that the MPG has 205/75/15 Load range C, the trailer has a 3500 lb axle and the GVWR is 3800 Lbs, 3500 lbs on axle, 300 lbs hitch weight. The load range C at 50 PSI is rated at 1820 lbs per tire or 3640 combined, single axle trailer. The load range D, 205/75/15 tires at 65 lbs are rated at 2150 lbs, or 4300 lbs combined. That will give a margin for weight and more protection against most road harzards. The rims will handle the 15 lbs extra tire pressure.

What does MPG stand for ?
If this is the same situation as for topicstarter, a upgrade would be wise, thoug the C-load can do.
I made 2 pictures for the C-and the D load in my caravan/trailer tyrepressure calculator, hope I can place them here after 2 posts.
Otherwise the link to the map on my skydrive , with the pictures and the spreadsheets also given.
https://skydrive.live.com/?cid=a526e0eee092e6dc#cid=A526E0EEE092E6DC&id=A526E0EEE092E6DC!348

this is the English version where I chanched kg to lbs, but it can also be added with American English ( tire instead of tyre, and preset at lbs and m/h. So if someone wants to translate load the spreadsheet and go to the languages sheet, how to translate is explaned there.
To use a spreadsheet first download it by right clicking on it and choose download. After download and eventual virus check, open it in Excell or Open Office Calc to use it fully . In the browser wont work because of sheet-protection and data validation I used in it.

 

[Sumo]

To quote Nike, "Just Do It"

 

[Ray LeTourneau]

Jadatis, "MPG" is the model name of the trailer. It's a smaller trailer similar to a larger type teardrop trailer. Heartland no longer offers this model but some may remain on dealers lot here in the States.
As long as the owner has wheels rated for the extra weight and psi capacity and doesn't increase the diameter of the tire too much, a change from "C" to "D" load range is perfectly acceptable. He would still need to keep the spring and frame capacity within the manufacturers GVWR specs.

 

[marc515]

Thanks guys; I'm not looking to increase any weight carrying capacity; only trying to put a better tire on our camper

 

[marc515]

I had a MPG 183(2011) which had the 5 spoke, 5 lug, Vision Legend 5, gun metal machined lip 15" rims, I checked all the sources Heartland, Treadit(supplier to Heartland, and did not get a defined answer, so off to the tire store, got the range D tires and had no problem with the tire pressure, but I would not go to tires that require 110 LBs with those rims. Couldn't find anything on the rims. I towed them a couple of thousand miles and they worked well. They were Mastertrac tires. They were 205/75/15, range D. The lugs were torqued to 100 lbs. I found a range of 90 to 110 # torque. no one wants to give answers that may involve liability!

Tumblebug,
Did you notice any increase in bouncing as a result of the higher tire pressure?

 

[marc515]

Well,.......here's a new twist.

According to Heartland Customer Service, the MPG rims are only rated to handle 50 PSI, and they do not recommend exceeding that pressure.

UPDATE: Just got ahold of the company that supplies the wheels to Heartland, and according to them, my wheels are rated to 65PSI.

 

[Tumblebug]

I had a MPG 183 that I put the D range tires on. The rims on the trailer were Vision Legend 5 -141 gunmetal machined lip. I contacted Tredit, they also indicated to me that the rims were rated to 65lbs. Had no problems and pulled the trailer about 3000 miles with that setup.
http://www.visionwheel.com/wheel.cfm?id=683

I have an extra hub cap if you need one.