Tire Pressure?

When someone says "tires" near me, I always ask if said person has heard of Roger Marble.

Roger is a very interesting guy. I know I captured him for a bunch of answers to some of my "Forever Questions" about tires one afternoon at an FMCA Rally.

So, if you want to know what really matters, look up what he has written and take it to the bank.

Matt_C

I have a 2011 31' Jayco Greyhawk. I used to set the tire pressure at 80psi all around. The front always felt like it was drifting. Not much fun to drive. I lowered the front to 75psi. Made a world of difference.

enblethen wrote:
first thing you need to do is weigh the rig ready for the road. Gear on board, fresh water and the like.
Then go to the tire manufacturer website and get the inflation chart.
Inflate the tires according to that.
I run five pounds over chart indicated pressure!

Winner,Winner, Winner! Ding, Ding, Ding! It is just that simple. :S

For the record I have 24' E-350 Class C, GVWR 11,500# and run at or very near that often towing a 2,500# Cargo trailer. 60 psi for the fronts and 65 for the rears gives me a 5 - 10 percent fudge factor and a very smooth /stable ride.

The folks who place the door tags have no clue how you are going to load/use your coach. The kid who recommended 80 psi is an idiot as that will guaranty a horrible ride. Over inflating the fronts will make the steering loosey/goosey as it reduces the contact patch.

Opinions vary as to when but tires time out, often long before they wear out. Had a tire grenade doing $4,181 in damage {it blew the wheel well right up through the bottom the coach}. It was less than 6 years old and had been inspected by Discount tire the previous day, had 6/32" of tread, looked great and was aired for the load carried. I now replace my RV 's tires at no more than 5.5 years and yes I live in Arizona which is a "challenging" environment {to say the least} for tires.

Folks who actually use their RV's on a regular basis will often approach wearing them out {5.5 years for us is easily 40,000+ miles}. I just replaced all 4 of my duallies with Michelin Agillis Cross Climates {my front tires and spare are all Agillis CC's and just a little over 2 years old}.

As noted,... Opinions and YMMV.

:C

Golden_HVAC wrote:
Ford put the same sticker on every E-350 they produce, and they know it will be put into a RV chassis, and should be close to the maximum GVWR. So if Ford says 65 PSI, that will give the most comfortable ride. 80 PSI and it will feel more bumps in the road. The tires should last 7 years - and you normally do not wear them out in that time.

You really should not keep the tires once they are 7 years old.

Fred.

Well, fortunately the OPs rig won’t have 7 year old tires for like 5 more years likely. But the “when to replace my tires?” recent threads could maybe use your advice, but not this one.

The change to motorhome wont change the GAWR's. So you would think it wont change the recomended pressure, because calculated for GAWR's, wich you are not allowed to go over.

But now, motorhomes are often overloaded and /or have unequal weight R/L on the axle.
So drive all the time with 100% or more of allowed weight on it.

Together with that most have tires with yust enaugh maximum load to cover the heavyest axle, makes it that they often need more then the maxloadpressure of yours 80 psi, to be safe to laws of nature.

So determine axleloads, or better axle-end loads acurate by weighing fully loaded as going on tripp, and give tire specifications, and I can calculate a pressure with maximum reserve, but still acceptable comfort and gripp for that.

Ford put the same sticker on every E-350 they produce, and they know it will be put into a RV chassis, and should be close to the maximum GVWR. So if Ford says 65 PSI, that will give the most comfortable ride. 80 PSI and it will feel more bumps in the road. The tires should last 7 years - and you normally do not wear them out in that time.

You really should not keep the tires once they are 7 years old.

Fred.

mikemc53, you said your rig is an E350 and you run it at 80-85% weight capacity ? That 350’s gvwr is 12,500 At 80-85% capacity you would be at 10,000-10,625 ? For a 30 ft class C, that seems very light to me.

What the door tag says is for gross weight. Until you have weighed it that is what you need to go with in my opinion.

They must have figured out how to build them lighter- I had a 1998 Gulfstream 30 foot C with no slides that ran about 13,700 loaded and 12K empty, on an E450 chassis. Having said that, those tire pressures are as recommended by Ford for a fully loaded vehicle. No reason to go any higher unless you are overloaded.

Being that a 6280 30’ non- slide has a gvwr of 12,500, i would think being careful packing it , you run it at or near gvwr. As said , look at that weight/psi chart.