Tire pressure- Force HD or DX3

Invisibleman · 03-12-2021, 05:40 PM

I'm expecting a soon to be delivered Force 37TSHD, and wondering what the typical placarded rear tires pressures to be. I want to order up a set of Cross Fire tire pressure equalizers for the rear dually's and need to get the right pressure setting. I've seen a lot of discussion on tire pressures on the forum, but I feel best using what the factory states on the door jamb. Worked for me well on my Isata-5.

mookieblaylock · 03-12-2021, 06:57 PM

All I’m gonna say is that every sticker on the door jamb shows/references 110 PSI...steer and drive. Enjoy the rest of the thread; it’ll devolve quickly.

Invisibleman · 03-12-2021, 07:01 PM

I'm betting you are absolutely correct, and exactly what I was looking for.
First rounds on me.

rskeans · 03-12-2021, 07:29 PM

I use 95psi all around.

Invisibleman · 03-12-2021, 07:34 PM

So why 95? Your door jamb says 110? I went through this with my Isata-5 that stickered at 95 and everyone said 85. I ran them at 95 because all the trucker forums and tire guys I contacted said use what the manufacturer says. I did, and i thought it rode great, and although I didn't have it long enough to tell, the tires seemed to ride nice enough. Not sure of why to just go below manufacturers specs. I'm going to stick with the 110.

Webefine · 03-12-2021, 07:42 PM

I run 95 all around also. Why, because I weighed my rig fully loaded and then went to the Michelin load/inflation chart for my tires and found 95 psi is what I needed with a little cushion.

Webefine · 03-12-2021, 07:50 PM

Another reason to weigh your rig and adjust your air accordingly. If the door sticker says 110 psi that would be enough air in the tires to carry the rig at the full GVW. When my DX3 is completely loaded I am still almost 5,000 pounds under GVW therefore I don’t need 110 pounds of air.

johndjmix · 03-12-2021, 08:00 PM

This is a very good and very unheard of thing in the RV industry (going to a scale it it being UNDER weight).

Many, many, if not most coaches...with just full tank of water and normal stuff you carry are over GVW. This is a major issue in the RV industry. My old fleetwood discovery pusher was over GVW always when loaded with normal gear.

Another reason to buy a Dynamax. Fully loaded we are UNDER weight!!!

—john

Magnatudes · 03-12-2021, 08:23 PM

Quote:

Originally Posted by johndjmix

Another reason to buy a Dynamax. Fully loaded we are UNDER weight!!!

—john

This is not 100% true. Many of the Dynamax offerings, other than M2 based, can easily go over the max weight. Especially I3. Lots of storage but hardly any CCC to take advantage of it.

johndjmix · 03-12-2021, 08:24 PM

Quote:

Originally Posted by Magnatudes

This is not 100% true. Many of the Dynamax offerings, other than M2 based, can easily go over the max weight. Especially I3. Lots of storage but hardly any CCC to take advantage of it.

Possibly. I should have been more clear...I was referring to the M2 based coaches.

—john

Magnatudes · 03-12-2021, 08:39 PM

Quote:

Originally Posted by johndjmix

Possibly. I should have been more clear...I was referring to the M2 based coaches.

—john

I would venture to say that any/all motorhome manufacturers that build a coach on an M2, not just Dynamax, would find it challenging to exceed the weight limits of the M2 unless your packing nothing but pure gold bars. Another reason why to buy an M2-based coach from any of several coach manufacturers.

Invisibleman · 03-12-2021, 08:47 PM

I doubt anyone expects anyone to adjust their tire pressure based on how much water and fuel they have at any given time. There are scales on the roads because truckers can have drastically varying loads and they have financial incentive to over load. Setting your RV tire pressure to placarded GVW and manufacturers spec is close enough for me.

M T Pockets · 03-12-2021, 08:50 PM

Ran 100 all around for first 6 months. Dropped to 90 F and 95 R. Rides better and no unusual tire wear after 15k miles. And as mentioned earlier, no where near max gross weight even with all the stuff I probably don't need to carry.

MoJoe1003 · 03-12-2021, 09:30 PM

Quote:

Originally Posted by Invisibleman

I doubt anyone expects anyone to adjust their tire pressure based on how much water and fuel they have at any given time. There are scales on the roads because truckers can have drastically varying loads and they have financial incentive to over load. Setting your RV tire pressure to placarded GVW and manufacturers spec is close enough for me.

If not at max weight and you run 110 all around you will sacrifice ride quality significantly. How do I know? I was an automobile dealer for 40 years and thought the same as you...run the tire pressure in the door. So, when I took delivery of my DYNAQUEST XL I made sure the tires were at 110. I barely had any cargo in it. After the first 500 miles I was sure I had made the worst mistake of my life buying a Freightliner based motorhome. It beat me and the coach stupid. I literally stopped on the side of the road and called Dynamax. Dynamax referred me to the Freightliner dealership where they buy their units. The first question the Freightliner guy asked me...Are you running 110 PSI in the tires? Answer, yes. After a slight snicker, he suggested I drop the pressure to 95 PSI. I did and WOW, what a difference in the ride! He said virtually ever complaint they get about ride quality is due to over inflation. Never looked back. Depending on the CAT Scale weight at any given time I may run 100 in the rear.
Do yourself a favor and don’t run 110 PSI unless, as others have said, you find a way to max out your GVW.

Webefine · 03-12-2021, 09:43 PM

Quote:

Originally Posted by Invisibleman

I doubt anyone expects anyone to adjust their tire pressure based on how much water and fuel they have at any given time. There are scales on the roads because truckers can have drastically varying loads and they have financial incentive to over load. Setting your RV tire pressure to placarded GVW and manufacturers spec is close enough for me.

I didn’t say I adjust mine for how much water or fuel I carrying on any given trip. I set the air in my tires to the weight of my rig fully loaded as I use it with some cushion in there.
For me it was about ride quality and tire wear so I went by what Michelin recommends for my weight.

Invisibleman · 03-12-2021, 10:03 PM

MoJoe. Very interesting. I've been around these tire pressure threads a few times. I am surprised you had such a bad ride with 10psi tire pressure difference. But I don't have any doubt about what you have said. In thinking back, the truckers are pretty much always running at GVW so no surprise they say max pressure.

MoJoe1003 · 03-12-2021, 10:12 PM

Actually, it was 15 lbs. However, it was very significant. Changed the whole dynamics of the ride and handling.

AWF1945 · 03-13-2021, 10:00 AM

I run 95 psi all around. 110 psi like others said is max load. With that said, if it makes you feel safer, run 110 psi.

Invisibleman · 03-13-2021, 10:13 AM

I appreciate the experience from you guys. 95 sounds like the magic number. Did you run crossfires? I did on my Isata-5 and I got 90's. I kept my tires at 95 but wanted the 5psi wiggle room in case I got a bit behind in airing up. BTW, do you know if you can voluntarily go through an interstate truck weigh station and get weighed? What's the procedure? Maybe its electronic nowadays and you need a gadget like an easy pass? Or, I am going to have my service done at a Velocity Truck Center here in Phoenix. I could ask them if they have scales. I'd like to know what my typical weight is, with fuel, and water. I usually travel with myself +1.

**bclemens** · 03-13-2021, 10:31 AM

Quote:

Originally Posted by MoJoe1003

Actually, it was 15 lbs. However, it was very significant. Changed the whole dynamics of the ride and handling.

Agree 100%. If you run at max pressure and don't have maximum load you will not get the same ride quality than if properly inflated. If you don't mind...then no worries.

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