Factory TPMS on Ford E450?

12 Gauge wrote:
I fear I know the answer to this already, but it's Sunday morning, can't call Ford, so will throw it out here.

I have been through the Ford manual for my new Forest River Sunseeker on a 2015 E450 chassis. I was very pleased when I came to the section regarding TPMS. Typically when optional features, e.g., Engine Block Heater, are covered in the book the tag "(IF EQUIPPED)" is attached. Since there was no "IF EQUIPPED" tag I thought it was great that I have TPMS. HOWEVER, there is no TPMS symbol appearing on the dash when the key is first turned on. Leads me to believe I don't have TPMS. Dampened my pleasure. Does anyone know if this should be a standard feature?

Also, the Ford data sheet calls for 75 psi from and 80 psi in rear dually. My practice in regular vehicles is to run at the max. Good idea for the RV?

I don't know if TPMS should be a standard feature. The Ford web site doesn't seem to mention it one way or the other, from what I could glean. Perhaps it was standard on their E-series vans but not on the chassis cab/cutaway models (as tire pressure requirements in those would vary depending on what was fitted to the chassis). The Ford manual for my motorhome chassis states that the jack for changing a tire is located inside the rear van door, despite the chassis never ever having been equipped with a van body.

Tire pressure should be based mainly on the load the tires will carry. For many passenger vehicles, running at the maximum pressure on the tire sidewall is way, way too high, and compromises handling and ride quality significantly. I would have to overload my Honda Fit by about 900 pounds (or put in twice the weight it's rated to carry) to need the tires at the maximum sidewall pressure.

In the case of your motorhome, the data sheet from Ford is probably based on the maximum axle ratings, and likely you are fairly close to those, so it's a reasonable place to start. Too much pressure in the front tires especially can lead to quite interesting and squirrelly handling on the E series chassis (more so than many other vehicles due to the comparatively crude front suspension design). Short of weighing it loaded for travel (always a good idea), I'd go with what the door sticker says, assuming it has one, and failing that the other literature.

You do want to make sure that both tires in a pair for the duallys have as close to the same air pressure as possible, which is more important than having precise agreement on opposite sides of the axle. Both tires in the pair have to rotate at exactly the same speed, and if one is slightly larger diameter than the other (due to air pressure differences), there will inherently be some scrubbing and more rapid wear.