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Discussion Starter #1
'15 PM 2500 diesel. Rode as one would expect when I drove it off the lot empty: harsh and noisy. Over the ensuing few months I've done a few things -- like incrementally dropping the tires down to ~63psi, removing the secondary leaf spring, and adding heaps of sound deadening material, insulation, and outright mass with my camper conversion.

And the truth is it rides and sounds a helluva lot better than it did when I bought it. Adding weight has made the biggest difference.

Alas my camper build is almost done -- no more weight to add -- and even when I have the van loaded to the gills for a 2-week roadtrip it still rides harsh. I'm talking about small bumps, and particularly square edged bumps. On new pavement all is right with the world, but old roads, concrete freeways with seams, or heaven forbid dirt roads with washboard -- and the noise and feel are intolerable.

My question is what to do about it?

I have the stock Nexen tires. I can't really go much lower on tire pressure than where I am now. Even if I could, I'm skeptical it would make the amount of difference I am after.

Is the solution to get a set of (non-E-rated) light truck tires? If I go this route, would the less-stout sidewalls and (I presume) lower pressures make a meaningful difference?

Or is the answer to leave the tires alone and dive into the suspension?

Open to any/all ideas.
 

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Have you considered an air-suspension conversion?

I don't have any first-hand experience with air suspension in ProMasters (but I have in a few Cadillacs, which rode nicely), so I don't know whether they are intended to improve ride quality or just offer better control of ride height.

It won't be cheap, though.
 

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My experience with non "E Rated" tires was on my sprinter. I ended up with a set of "C" rated winter tread. Biggest difference I noticed was the amount of left and right sway the van had. I drove it that way for a couple of days and had the tires switched out, as the sway was bad.
 

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I have the same complaint! In fact it's the only complaint I have about my Promaster. I believe the problem is two fold - both the tires and springs are totally unsuitable for a camper/passenger vehicle. I'm sure in the rest of the world much softer springs and tires are the norm for Promaster campers and people haulers but in N.A. The powers to be have determined that all Promasters will be used to carry freight and should be white. Another typically bad marketing decision by Chrysler with full support from Fiat, obviously.

I've made all the modifications you have plus added air shocks with hardly any difference in ride at all. I believe the only real solution is to source out softer springs from Europe and replace the tires with something more passenger friendly.

I have a '14 high, 159 gas and I do believe this is a much larger problem with the 159 for obvious reasons.
 

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Could you tell us more about the spring change. I was going to have my springs re-arched but my schedule has interfered. My 1500 rides like a truck but not as bad as you describe, I have the tires at 65 and the back sits too high so does the spring change help that? A couple of posters have gotten their dealer to recalibrate the TPMS to allow them to lower the pressure with good results. I’d go down to 55 if I could.

Here is an air suspension:
http://www.vbairsuspensionusa.com/u...Product sheet VB-FA-4C RAM ProMaster V1.0.pdf
 
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It would be cheaper to fly to Europe and buy the correct springs designed for passenger and/or campinrs and bring them back on the seat next to you than pay for that solution!

I think we have to determine if the window versions of the Promaster have different springs. I know there seems to be some data to suggest the springs on different versions of the Promaster are different from comparing parts numbers but no real data seems to be available.

As a side note, my '04 Sprinter was a passenger model and rear suspension problems were nonexistent. Perhaps the only problem I never had with the Sprinter, but that's another story ;)
 

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Discussion Starter #7
Could you tell us more about the spring change. I was going to have my springs re-arched but my schedule has interfered. My 1500 rides like a truck but not as bad as you describe, I have the tires at 65 and the back sits too high so does the spring change help that? A couple of posters have gotten their dealer to recalibrate the TPMS to allow them to lower the pressure with good results. I’d go down to 55 if I could.

Here is an air suspension:
http://www.vbairsuspensionusa.com/u...Product sheet VB-FA-4C RAM ProMaster V1.0.pdf
As a first attempt at solving this, I simply removed one of the leafs on each side out back. Actually had a tire place do it while they were installing new wheels. They fabbed up a small spacer to take the place of that secondary leaf, and to be able to re-use stock hardware. It does lower the rear end height -- something like 1.25" IIRC.

I had my dealer recalibrate my TPMS to the lower pressures I like to run. At low speeds (entering/leaving parking spaces, for example) and anything other than steering wheel straight, I'm already uncomfortable with the level of 'scrub' that I can hear from the tires at 63psi. Also have noticed an overall ~2mpg decrease at these lower pressures. For both of those reasons I'm not willing to go lower.

I'm going to weigh the van this AM, then head to a tire place with those #'s in hand to discuss potential tire options. My gut tells me that both tires and sus need amending to improve the ride to the level I want it improved. My head tells me that the harshness is much, much more tires than sus.
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
For the last three trips in our PM camper, I've run the tire pressure at 52 psi. This is based on my actual fully loaded axle loads plus some safety margin and the Vanco load-pressure table. It does make a noticeable difference in ride -- the ride seems OK to me even when riding in the back.

I keep careful track of gas mileage, and I believe there is a hit, and I would put it at 1 to 1.5 mpg. I used to average about 19.5 mpg (depending on the terrain, weather, ... ) -- for last 3 trips its been more like 18.5 mpg.
I'm sensitive to mpg, and may bump the pressure up a bit to try and recover part of the lost 1 mpg.

My van is a 136 WB.

Gary
 

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I have a 2015 2500 159WB gasser DIY camper. I run 62 PSI in the tires. Loaded my rig weighs 7000 pounds almost equal of 3500 per axle. I am very satisfied with the ride. If your van is under 7000 pounds you might add more weight. I wonder: does anyone know if the diesels have stiffer springs front or rear than the gassers?
 

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Discussion Starter #10
Thanks for the thoughts, people.

I too wonder if the window vans have a different suspension configuration from the cargo vans?

I weighed my van this AM and came up with these #'s:
3680# front axle
2840# rear axle
6520# combined.

I will sometimes run it as much as ~600# heavier when *really* loaded for a long trip, but more likely it will be right at these weights.

Based on those #'s I can *safely* (<-key word) run as low as low 50's for psi in my van. I may indeed try lower in the rear tires for a bit, but am not interested in going lower on the fronts for the reasons listed above.

Armed with the weights above, I stopped by my local Big O tire place. I've had a slow leak in my right rear tire for a ~week, and needed that attended to. While I waited I bent the ear of a few of the sales guys about the ride quality. Long story short, they suggested I try a set of Michelin tires. One of the guys tried to explain how Michelin had some patented formula for their rubber or casing structure that was designed to deliver a "better" ride, but couldn't quite come up with any facts to support his assertion. Regardless, what he did do was to offer to install them and let me drive 'em around for a ~week risk free. If I don't feel the difference I take the van back and they reinstall the Nexen's, no charge. Hard to argue with that offer. He also offered to come up with a trade-in credit for the Nexen's if I like the Michelin's.

Currently waiting for him to quote the Michelin's, so that I can assess whether this whole venture is worth considering.
 

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Discussion Starter #11
Have you considered an air-suspension conversion?

I don't have any first-hand experience with air suspension in ProMasters (but I have in a few Cadillacs, which rode nicely), so I don't know whether they are intended to improve ride quality or just offer better control of ride height.

It won't be cheap, though.
My understanding is that I'd gain a lot of benefits in ease of adjusting ride height, but almost nothing if not a backslide in ride quality.
 

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I can adjust my height but I have no real need to after it's been set unless I'm towing a trailer. The ride is slightly better but certainly not worth the $500 the set up cost. The height was too low when I removed the helper spring however.
 

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2014, 138WB, High Roof, Gas, SW MT
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Thanks for the thoughts, people.

I too wonder if the window vans have a different suspension configuration from the cargo vans?

I weighed my van this AM and came up with these #'s:
3680# front axle
2840# rear axle
6520# combined.

I will sometimes run it as much as ~600# heavier when *really* loaded for a long trip, but more likely it will be right at these weights.

Based on those #'s I can *safely* (<-key word) run as low as low 50's for psi in my van. I may indeed try lower in the rear tires for a bit, but am not interested in going lower on the fronts for the reasons listed above.

Armed with the weights above, I stopped by my local Big O tire place. I've had a slow leak in my right rear tire for a ~week, and needed that attended to. While I waited I bent the ear of a few of the sales guys about the ride quality. Long story short, they suggested I try a set of Michelin tires. One of the guys tried to explain how Michelin had some patented formula for their rubber or casing structure that was designed to deliver a "better" ride, but couldn't quite come up with any facts to support his assertion. Regardless, what he did do was to offer to install them and let me drive 'em around for a ~week risk free. If I don't feel the difference I take the van back and they reinstall the Nexen's, no charge. Hard to argue with that offer. He also offered to come up with a trade-in credit for the Nexen's if I like the Michelin's.

Currently waiting for him to quote the Michelin's, so that I can assess whether this whole venture is worth considering.
Hi,
You can use the tire manufacturers tire pressure vs load tables to determine what the the manufacturer recommends for the tire and load you have.

This post I started early shows the procedure:
http://www.promasterforum.com/forum/showthread.php?t=47137

As an example, for the Vanco tires I have the tire pressure vs load tables are here.
http://www.conti-online.com/www/dow..._info/download/technical_data_book_pdf_en.pdf
You would have to find the tables for the tire you end up choosing, but one comment on the post mentioned above is that the tables for different tire manufacturers for the same size tire are essentially identical.

I was concerned about the safety of running pressures that are much lower than the door sticker, and did quite a bit of looking around to assess safety -- my conclusions:
- Using the the manufacturers tire pressure vs load curve to choose pressure is safe-- its what the maker of the tire recommends as the best pressure for a given load.

- I found a couple published articles on selecting tire pressure and they basically used the tire pressure vs load method mentioned above.

- I've done several trips and several thousand miles with 52 psi with no problems -- I've measured tread and sidewall temperatures after long runs as highway speed and the IR temperature gun readings seem fine (although I've not been able to find anything on what the max temp the tires should run at).


I'm planning to change tire brands when my Vancos tread depth goes down a bit more, and would like to get something that rides better and has low rolling resistance, so I'll be really interesting in what you find with the Michelins (or whatever you chose).

Gary
 

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Do some research into air ride seats, let the van bounce around under you, use just a 12 Volt air compressor for supplying the air to the seat, they are available in many shapes and sizes...
 

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Nothing wrong with the front suspension, it's the rear that's much to hard so air seats won't improve the ride (unless you are sitting by the rear doors)!
 

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I'm at 6000 lbs.

Went from Vanco to Michelin LTX MS/2, both at door sticker air pressure

Huge improvement in comfort. Never realized just how much the Vanco made it truckish

Feels like an SUV now.
 

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I think that van and car manufacturers put recommended tire pressures on the door stickers that are appropriate for the vehicle at max gross weight. This is for safety and to cover their fannies legally in the event of an accident. In fact, I believe the Feds require that approach. Most of our DIY campers are well under and around 60 to 65 PSI seems to be a commonly used pressure. Having owned two Sprinters and followed that forum in past years, pressures in the low 60s seem to be common for those folks also.
 

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I'm at 6000 lbs.

Went from Vanco to Michelin LTX MS/2, both at door sticker air pressure

Huge improvement in comfort. Never realized just how much the Vanco made it truckish

Feels like an SUV now.
I had those on my sprinter, great tires. I may get them for this van soon, very good in the snow also
 

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My 2014 2500HT 159 weighs just under 8000lbs when loaded for a trip (4010 front - 3950 back) - before I climb aboard.

I recently had Cooper Discoverer AT3 LT245/70/R16 installed that I inflate to 68lbs and the ride seems to be much better. So I would agree that tires can apparently make a difference in the ride/handling of the ProMaster, YMMV.
 

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Discussion Starter #20
Hi,
You can use the tire manufacturers tire pressure vs load tables to determine what the the manufacturer recommends for the tire and load you have.
Yep, I've used the psi/load tables to get in the ballpark. I know I can go lower, I simply choose not to, for my own reasons.

Just waiting for the sales guy to send me a quote on the Michelins.
 
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