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Old 03-06-2016, 05:57 PM   #11
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The comfort, handling and performance of my 2016 DX3 is satisfactory, but there is room for improvement. For that reason, I am responding with the following observations and recommendations on the issue you present--tire pressure and ride quality, handling due to wheelbase, handling in general, and power.

Tire Pressure and Ride Quality
Michelin’s recommendations on tire pressure based on load is good advice. On forums and at rallies, the recommendation is to load a motorhome as it is normally used, weigh each wheel, and inflate the tires according to the tire manufacturer’s recommendation. The recommendations of the vehicle manufacturers, which is frequently based on the fully loaded chassis, is conservative and the next best advice. Tires lose pressure. Tire pressure is frequently ignored by drivers with the consequence of the vehicle being driven with under inflated tires. The consequences of underinflated tires is more severe than over inflation, as long as the tire and rim manufacturers’ recommendations are not exceeded.

In Oregon weighing a vehicle is easy. “ODOT scale decks are operational 24/7 for public use, including when the sign on the highway may indicate the scale is unmanned and is closed. As you cross or stop on the scale deck, your weights will be indicated on the scale reader board. The only time scale decks are closed to the public is during repair status.”

Whenever, I brought my motorhome on a Ford E-450 chassis to a Ford dealer for service, they inflate all the tires to Ford’s recommended tire pressure, which is for the fully-loaded chassis.

My practice has been to keep tire pressure between Michelin’s recommendation for the specific weight on the tire and the vehicle manufacturer’s recommendation, and I watch thread wear. I use a tire thread gauge and aim for an even thread wear across the tire for maximum thread life, and will adjust pressure to achieve it. Thread wear is diagnostic of under/over inflation as well as alignment issues.

When measuring thread depth over time, the same exact locations on the tire must be measured or representative sampling must be conducted, as thread depth will vary with location around the circumference of the tire.

An under inflated tire wears more on the sides than in the middle; an overinflated tire wears more in the middle than on the sides. Misalignment can cause other thread wear patterns.

Under inflation allows for a softer ride, causes more tire flexing, increased tire temperature, and premature tire failure. As Michelin says, “An underinflated or overloaded tire will build up more heat that could go beyond the endurance limits of the rubber and radial cords. This could cause sudden tire failure. Underinflation will also cause poor handling, faster and/or irregular tire wear, and can decrease fuel economy.” Michelin RV Tires, p. 3.

Over inflation makes for a harsher ride, reduces rolling resistance, reduces tire temperature, and improves fuel economy. As Michelin says, “Overinflation, on the other hand, will reduce the tire’s contact area with the road, which reduces traction, braking ability, and handling. A tire that’s overinflated for the weight it’s carrying is more prone to a harsh ride, uneven tire wear, and impact damage.” Michelin RV Tires, p. 3.

Michelin RV Tires can be found at

Another good Michelin reference, a little more extensive than the foregoing, this one for trucks, can be found at

Tire pressure monitors, some with auto inflate, seem to be growing in popularity among vehicle owners. This link is for a Michelin offering

Handling Due to Wheelbase
A “short-wheelbase vehicle is difficult to control when driving on slippery, gravelly, or wet roads and that they have a propensity to wander,” according to RV Consumer Group

RV Consumer Group views a wheelbase to length ratio of less than 60% as substandard and recommends a ratio of 70%. They rated the 2015 Dynamax models and floor plans from 76 (3.5stars) to 91 (5 stars).

If the wheel base is long, there is a concern of driving over curbs when making turns. If the wheel base is short there is a concern that the rear with pivot on the rear wheels to cause damage to adjacent vehicles and structures, and the rear might hit the ground when changing grade.

Handling in General
Last year, I attended a lecture by Henderson’s Line-Up and Super Steer Products at the Family Motor Coach Association Northwestern Area Rally. The instructor from Henderson first described for the Ford E-450, hardware that might be added to improve handling in the order of the greatest improvement for the least money. He devoted most of his time to describing hardware that might improve ride and handling for the Freightliner chassis. The lecture was not applicable to the M2 chassis.

Common ride and handling problems for motorhomes are described at
and at

Diagnosing problems with ride and handling is not easy. The most common handling problem with the Ford E-450 is the need to continually correct steering. Clearly a front end problem? No, the problem is the “Tail Wagging the Dog: Typically caused by excessive lateral motion of the rear axle.” This phenomena causes continual steering correction to keep the vehicle going straight. I know the problem only too well, but I would not have known enough to attribute the problem to the rear axle. There is relatively inexpensive hardware that attaches to the frame and axle that allows vertical motion but not lateral motion of the rear axle.

The second recommendation Henderson made for the Ford E-450 was for hardware to improve front end handling, including a front tire blowout. Forum discussions and several videos I have seen, indicates a driver of a motorhome will need all the help he/she can obtain to prevent damage and injury in the event of a front tire blowout at speed.

For me, the most troubling handling characteristic is due to wind, including the passing of large vehicles. This problem is much less with the DX3 than it was for the Lazy Daze on the Ford E-450 chassis.

When I drove a 2015 Seneca, in my opinion it was under powered relative to the Lazy Daze with the Ford E-450 and 6.8-liter, V-10. The Seneca has the same torque as the Force. I would not want less power than available in the DX3.

The DX3 handles well, better than most motorhomes on the road, as noted by RV Consumer; and the DX3 rides comfortably. Recommendations are:
· Add Michelin RV Tires and RV tires pressure charts to the Dynamax USB memory stick of Dynamax manuals
· To improve handling increase wheelbase to length ratio.
· To reduce the effects of wind on handling revert to the attractiveness and practicality of the sleek, aerodynamic old Dynaquest, which had a one foot lower height than the 13¼-foot height of current Dynamax models.

2012 Lazy Daze 24’ FD (for sale)
2016 DX3

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Old 03-06-2016, 06:10 PM   #12
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Good notes, the tire pressure data makes good sense.

Last check on the DX3 however was 12'9" to the top of the A/C.

PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).
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Old 03-06-2016, 06:18 PM   #13
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Originally Posted by bclemens View Post
I wish we could "star" or "like" posts here. Admin?
You can actually "star" threads on the web version, but not posts. On top of the top post on a page or thread, there is a rate thread dropdown box, which allows you to assign it from one to five stars.
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Old 03-23-2016, 05:17 AM   #14
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As Dutch Pigheaded selfdeclared tirepressure specialist , I determined in time a border for comfort.
That is if real weight on tire is below 85% of the weight the pressure is calculated for for 99m/h .
Example: when pressure is calculated for 1000 kg/lbs whatever , then when real weight on tire is below 850 kg/lbs , discomfort by bumping begins.
Ofcource this is subjective and discussable..
Call this the Loadpercentage shortened by L%

Below 80 % L% , even screws can tremble loose , so this is the lowest for travel-trailers, wich have no persons ( or animal) in it .

This all for the average tire, with Hight/width division of above 65%.
Has everything to do with the deflection of the tire, a low H/W tire maybe even would give discomfort at L% of 100 %., but luckyly Recreation Vehicles are not pimped up with these kind of tires.

Then this pressure must be calculated with the ever to be constructed ideal formula , and the official American formula for tires above C-load is sertainly not the ideal one. The European one is better and adequate for Standard load and XL/reinforced/Extraload, and American tire makers organisation stepped over to this formula as late as 2006, but only for SL and XL//, and left C-load and up to the old calculation.
The calculation in America for SL and XL// was verry bad before that, that for LT tires ( above C-load ) was less worse and still is.
For LT and trucktires even the european calculation , wich is used for every kind of tire since decades, gives a bit to high loadcapacity's for the presssures, or the other way around , a bit to low pressure for the load on tire.

Then its also important wich data you put in the formula.
If one is not determined accurate enaugh , the answer is still not reliable.
Most tricky part is the determination of the weights on the seperate tires, but 4 point weighing loaded as driven, is the most accurate way.

Pressure advice is also dependent on actual speed in relation to the speed the maximum load of tire is calculated for.
You can also calculate a lowest pressure at wich the tires wont damage by overheating for the maximum speed you drive , and wont go over for even a minute.

If pressure is kept between lowest advice for no damage, and highest advice for comfort , you have maximum reserve, no damage to tires, so longer livetime of tire and chanche on blowout is practically zero.

This all if all is determined 100% acurate and that never is.
Pressure measurement can be inacurate, even if you have a digital device, wich suggests 100% accurate because it gives pressure to 2 digits behind the point.

Then the weight is often estimated, so sertainly not 100% accurate.

But also the specifications on sidewall can be different from what would be right to laws of nature. Also misunderstandings by conversions between different markets .
Example: USA C-load /LRC has pressure behind AT of 50psi.
Is often compared to EUR 6PR( plyrated) wich AT 55psi.
If then European brand sets it in the market in USA , and puts C-load on sidewall with the maximum load calculated for 55 psi , the presssure calculates to low when 50 psi is filled in the formula, wich is done in the past to my conclusion , and still is done.

And its important for wich speed the maximum load is calculated.
For ST tires its calculated for 65m/h , but often you see N speedrated on sidewall, wich is max speed of 140km/86m/h, and it suggest the maximum load to be calculated for that 86m/h.
Lower speed means lesser cycles the tire makes a minute/second whatever.
Lesser cycles means that the tire can produce more heat a cycle , so more deflection allowed,
So its best to calculate the pressure of an ST tire for the virtual speed of 160/99m/h , to get the same deflection an LT tire with speedcode Q of same sises and loadrange would have.
And then even make minimum L% per axle 85% for maximum reserve without bumping.

If experiënce proves that L% of 90% is comfortable for you , go from that lowest border. But always keep tire with highest weight on the axle below L% of 100%.
95% is what I advice to cover the inacuracy and pressure-loss in time.

Best is to keep the pressure to the highest border , so inacuracy is covered.
Can be that you determine this highest pressure with acceptable comfort and gripp, and by all the inacurate data this pressure is in real yust enaugh to be at the lowest border for no damage.
At this lowest border ofcourse even more comfort.
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Old 03-23-2016, 05:52 AM   #15
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I have to either Quit Drinking or Quit Reading? ^^^^^? Youroo!!

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