Tire Pressures

[mtntrek]

Originally Posted by dtw1

Thanks so much for the info on the tire pressure situation.
Why do some of you run cold tire pressure at 125 psi?
Some of you think the pin weight is low at 3610 lbs. Why?
Some of you commented the trailer may be high on the truck. What measurement should I use to determine this? It does not appear to be that nose high when hooked up to the truck.
With trailer - Total weight 13,770 lbs
LF 2,650 RF 2,610 Total weight on front - 5,260
LR 4,260 RR 4,250 Total weight on rear - 8,510
Actual trailer weights using the Smart Weigh System
Trailer weight - 14,950 plus pin weight of 3640 = 18.950 lbs
LF - 3,750 RF 3,050 total weight on Front - 6,800 lbs
LR - 4,150 RR - 4,000 total weight on Rear - 8,150 lbs

Perhaps some don't understand the "Smart Weigh System"?
Why do some of you run cold tire pressure at 125 psi?
Because there is really no reason not to run the max sidewall capacity. Max load 125psi @ 4800 lbs. is only 10% reserve over your
RR 4,250lbs. Is cutting it a little close for anything less IMO. Hot pressures are somewhat irrelevant, well unavoidable. Focus on temp discrepancies between similar wheels.
Some of you think the pin weight is low at 3610 lbs. Why?
Perhaps not alarming for an empty trailer. But who uses an empty trailer? At your Gross 20K we'd probably expect to see something in the 4,200 lbs. range. Roughly 20% but it varies, most pack heavy.
Some of you commented the trailer may be nose high?
The difference between the trailer axle weights is distinct. Many of us would hope for them to be slightly closer. This is why many equip with the frame risers running more recent model trucks that sit higher than older models. Nose high is common with 5r's while maintaining TV bed to Trailer cap clearance.
What measurement should I use to determine this?
Level ground. The lowest portion of the trailer frame members that the suspension components attach to, fore and aft perhaps 10ft. Compare the two. But axle weights are often the proof of the pudding.
Naturally perfection is not possible, but do enjoy your travels.

[wingnut60]

mtntrk,
Good answers.
Wonder if DRV has moved the axle location in the years from '12 to '16? That might explain the lower PW on the '12.
Also note he is over the 8k rear axle by a small amount, not a big deal. I am running at max on my 8k axles.
Sure having a wonder about the front/rear weight differential if not nose high.
Will be interesting to solve this--
Joe

[Cummins12V98]

Originally Posted by Porthole

???
Not sure what you are getting at.

My pin weight # of 4000 was based on CAT scale #’s

Sorry got you mixed up with the op!

[MS60ocb]

Originally Posted by wingnut60

mtntrk,

Wonder if DRV has moved the axle location in the years from '12 to '16? That might explain the lower PW on the '12.

Joe

Do you have measurements to compare with for a particular Year? The measurement your talking about is PIN to Front Axle?
My MS 38PS3 is modified enlarging Closet and Bath Room. The PIN to Axle 19 - 20 feet but will confirm. The PIN weight is 25% I running nose low as I had ordered RV with 2 inch risers as I had a Ford dually 4x4. Since I traded I need to have a 2-3 inch shim for under hitch.



Clay

[kannon]

Originally Posted by MS60ocb

Do you have measurements to compare with for a particular Year? The measurement your talking about is PIN to Front Axle?
My MS 38PS3 is modified enlarging Closet and Bath Room. The PIN to Axle 19 - 20 feet but will confirm. The PIN weight is 25% I running nose low as I had ordered RV with 2 inch risers as I had a Ford dually 4x4. Since I traded I need to have a 2-3 inch shim for under hitch.



Clay

The owner of comfortride hitch told me manufactures are moving axles forward to lessen pin weight to give the uninformed the illusion you could pull with a lesser tow vehicle.His hitch relies on pin weight to work at its best.About 1 to 1.5 inches crush on its pucks.His remedy is to add weldments to hold 2 straps to preload some "artificial" weight.I believe I have one of the 1st hitches with that setup.Dont need that as I have 4k pin weight,but its on if I sell hitch.

[Porthole]

Originally Posted by kannon

The owner of comfortride hitch told me manufactures are moving axles forward to lessen pin weight

That's an interesting quote.

Who here has 39DBRS3's and would like to compare front axle to pin, rear axle to cap?

I still think my pin weight is less then I was expecting, based on the conversations here and on the other forums. I was expecting close to 5000 pounds, especially having a heavier then normal generator and and fuel tank, 3K inverter and the two extra batteries.

The way my trailer pulls, rides, pin weight and the bounce we have when set up makes me wonder if the axles are to far forward. The "bounce" I have may well be other issues. My leveling leaks down over a few days and I really think the rear jacks are to far forward, they are just behind the rear wheels.

My last trailer was rock solid on the jacks, only felt movement when the the combo washer dryer was in the spin cycle. This trailer - every time I get up and move around at night my wife says the shake wakes her up.

[MS60ocb]

I measured my RV today. I said previously I thought the PIN to Axle measurement was close to 20 feet. I was off a couple dozen inches. The PIN to front axle is 23 feet 11 inches. The axle separation is 36 inches. Rear axle to rear of RV is 12 feet. The rear Jack is 30 inches behind the Axle. The front rear jack is 24 inches ahead of the axle or total separation of rear jacks is 7feet 6 inches. My front jacks are 16 feet 5 inches from the front axle or 7 feet 6 inches behind the pin.
Overall RV length 40 feet 9 inches MS38PS3/Dallas Mod S/n 8120
Clay

[wingnut60]

When I posed the thought earlier about moving the axles, I have no basis in fact to back that up--was just a thought. I cannot imagine DRV/Thor using fuzzy engineering to reduce pin weight.
However, also cannot see how any of these 38ft+ trailers can have less than 4-4200lbs pin weight without the axles being moved forward, or an inordinate amount of weight being placed behind the axles. Maybe some of the floorplans do this....
Again, just my thoughts.
Joe

[Cummins12V98]

"This trailer - every time I get up and move around at night my wife says the shake wakes her up."

These will make all the difference!

[Porthole]

I'm going to make up some blocks - but I really can't see why we should have to do this with the Leveling system.

Im sure the jacks leaking down is not helping any.

Originally Posted by Cummins12V98

"This trailer - every time I get up and move around at night my wife says the shake wakes her up."

These will make all the difference!

[rynosback]

Originally Posted by Porthole

I'm going to make up some blocks - but I really can't see why we should have to do this with the Leveling system.

Im sure the jacks leaking down is not helping any.

The less the jacks are out the more stable the unit is. When we are sloped with the nose low, the rig does not move.

[Porthole]

Yeah, I get the idea - but on my last trailer that was not an issue. When I look at the side profile of the trailer it looks like the rear end is hanging way to far over to be stable.

I may try and measure tomorrow, but this picture will give an idea of what I am referring to

The 3 jacks are almost equidistant, but all three are on the forward 2/3's of the trailer. The trailer bounces when you walk around the back end.

[wingnut60]

When looked at from the side, sure seems a lot of overhang. Haven't thought about it that way.
I always block the jacks no matter how level the site is, to keep the extension to a minimum. When at an off-level site, use more blocks on the higher side/end. Ours is basically a foot shorter and does not seem to have a bounce problem at the rear area.
DRV/Thor is pushing the limits with 2 axles under these heavy units, even with 9k IS use.

[Porkchop]

My 44' has the jacks set about like yours so I have more hang over. We do use blocks to keep the jack extension short and have never had a shaking problem.

Bill

[Porkchop]

OH crap! I disagreed with someone! Will fhenn show up and lock this thread now?Bill

[Fulltimer50]

Originally Posted by Porthole

Yeah, I get the idea - but on my last trailer that was not an issue. When I look at the side profile of the trailer it looks like the rear end is hanging way to far over to be stable.

I may try and measure tomorrow, but this picture will give an idea of what I am referring to

The 3 jacks are almost equidistant, but all three are on the forward 2/3's of the trailer. The trailer bounces when you walk around the back end.

While I have not seen every DRV there is, I have noted that non of the pics that I have seen of the two axle rigs show the jack located like yours. Only on the triple axles have I seen the jack forward of the door.

Of coarse right after I posted this I found at least one 2018 with the jack in front of the door. Maybe the floor plan is the key.

[wingnut60]

Hadn't noticed that before--mine is just in front of the tire and behind the steps. Will start looking at that now. Cannot see how that would affect the pin weight--also seems more logical to move the rear jacks more to the rear. ????
Joe

[Porthole]

Originally Posted by wingnut60

DRV/Thor is pushing the limits with 2 axles under these heavy units, even with 9k IS use.

Have to agree. Our brochure listed dry weight is 16,800. I know we put a few options on the rig, but we didn't load it up with every option and it doesn't have granite countertops and we are still at the GVWR of 21.

I don't see how a loaded Elite model can be within those numbers.
Maybe MOR/ryde will have 10K suspension available in the near future, or DRV makes 3 axles available on the shorter RV's.

Living in the northeast I have always been against the 3 axles just because of the tolls. And that is the reason on each trailer I sized them to be under the 3 axle requirement.

If MOR/ryde does come out with a 10K version I suspect we may be in Elkhart doing an upgrade.
ended up doing that on our previous toy hauler. Went from 7K IS to 8K IS

At least the G-114's running at 125 PSI have some reserve on the 2 axles. But having had a G-114 blowout a couple years ago has me always wondering where the limits are.

[Porthole]

Originally Posted by Fulltimer50

While I have not seen every DRV there is, I have noted that non of the pics that I have seen of the two axle rigs show the jack located like yours. Only on the triple axles have I seen the jack forward of the door.

Of coarse right after I posted this I found at least one 2018 with the jack in front of the door. Maybe the floor plan is the key.

I haven't really taken notice before, as I didn't know it was an issue. Where have you seen the jacks typically? Between the
steps and the front axle?

Originally Posted by wingnut60

Hadn't noticed that before--mine is just in front of the tire and behind the steps. Will start looking at that now. Cannot see how that would affect the pin weight--also seems more logical to move the rear jacks more to the rear. ????
Joe

Jack placement and pin weight no, but axle placement? Definitely.
Not an engineer and math was never my best subject. But I think if the axles were a foot or two further back my pin weight would increase 3-500 pounds. And that would force the rear jacks further back which would add stability. May make for a better towing experience as well.

Lippert has made axle placements incorrect in the past. There were approximately 100 Heartland Bighorn models where the axles were placed incorrectly. There was a NHTSA recall on the RV's and the fix was to take the front axle and relocate it behind the rear axle and re-do all the J-wrap.

That is the equivalent of a 3 foot error!
And the side effect to the issue is the repair quality. I have 3 friends that had the axle relocated and have since had the spring hangers break off the frame. Granted, Heartland has had plenty of spring hanger failures, but the poor recall repairs exacerbate the problem.

[Fulltimer50]

The jack placement is relevant to the thread of stability when level.
I think the jacks are leveling jacks and as such should be placed where they can lift the most weight safely and not damage the frame.