Proper tire inflation of F-150 pulling Cougar 22 MLS

[Wis Dan]

New member and new owner of the Cougar 22 MLS. I have E-rated Cooper Discovery tires on my F-150 - 275/60/R20. I run at 50 psi for regular driving. I'd like to lean on the expertise of this forum for advice on the proper inflation when pulling my TT. The 22MLS is approx. 6100 lbs dry weight. What do you guys think? I'm guessing 60 front and 65 back?? Higher?? Let me know.
Thanks in advance!!

 

[RacerX-KEY]

More important than towing weight is tongue weight and the total gross vehicle weight including tongue weight, passengers, fuel, cargo etc on the F150. You can assume tongue weight is 10-15% of total trailer and is estimated at 645 by Keystone. But depending on how you are loading it will be different. With your F150 it is easy to exceed your total cargo carrying capacity but knowing how much the tires are actually carrying will help determine what the inflation should be.

 

[wiredgeorge]

The tongue weight Keystone lists is a fantasy; your tongue weight will be about 1000 lbs with the camper fully loaded. Suggest you air your LRE tires to 80PSI when towing to get the full benefit of load range E tires.

 

[NH_Bulldog]

When I had my F150 towing my Passport 240BH, I upgraded the tires to Load Range E (LRE) and ran them at 70 PSI. With road heat, they typically increased to 75 PSI while towing. Because of the weight distribution, I kept both the front and rear the same pressure.

 

[Notanlines]

I’m with George, Run at 80 max psi, if that is what the sidewall says. That’s why you bought load range E.

 

[Wis Dan]

Thanks guys! I appreciate the feedback.

 

[flybouy]

Just realize that the E rated tires will help handling it will not change the axle ratings, the payload capacity, or the gvwr of the truck.

 

[NH_Bulldog]

Just realize that the E rated tires will help handling it will not change the axle ratings, the payload capacity, or the gvwr of the truck.

Actually it does change those things, it REDUCES them! Any added weight to the vehicle that was not in/on the truck the day it was manufactured deducts from the capacity ratings.

 

[Rhagfo]

I’m with George, Run at 80 max psi, if that is what the sidewall says. That’s why you bought load range E.

Running an E rated tire at 80 psi on a F150 is way over inflated! Axle rating at what 4,800# each tire ratted at well over3,000# ea equals loss of traction.
Get the inflation chart and weigh the loaded rear axle and match inflation to load.

 

[flybouy]

Rob, I think your splitting hairs there. First, the tires on the ground are not supported by the suspension. If a difference in tire weight was impactful, then those weight ratings would only be valid with the OEM tires. Replacing the tires should not cause much weight variation as long as they are identically sized.

 

[NH_Bulldog]

It could be argued that it is splitting hairs, (maybe it's the engineer in me) but consider that a vehicle's cargo capacity is determined by subtracting the vehicle weight (curb weight) from the GVWR, so increasing the weight of the truck whether it is sprung weight or not, does reduce the cargo capacity of the truck. Air bags, helper springs, heavier duty tires, mudflaps, tonneau cover, push bumper, etc. all add to the weight of the vehicle and so reduces the cargo capacity by a corresponding amount of weight. Depending on how close someone is to the "edge", adding 24 more lbs. of tires could be the straw that broke the camel's back......

 

[flybouy]

While True what's the relevance? If a clock is off by one second/week is it inaccurate? Technically yes but the "real world" relevance is minimal and not noteworthy IMO.

 

[NH_Bulldog]

speaking of clocks; I have a watch that receives a signal from the Atomic Clock in Fort Collins Colorado every day at 2 am. and that is what I use to set all my other clocks. So yes, one second a week would bug me

 

[flybouy]

Wow, I guess I'm not important enough to concern myself with such precision. If I start launching missiles or building nuclear reactors in my old age then I'll review the need.

 

[NH_Bulldog]

Careful "they" are watching and listening to us....

 

[flybouy]

Careful, I may be one of "them" myself!

 

[Stu Norman]

speaking of clocks; I have a watch that receives a signal from the Atomic Clock in Fort Collins Colorado every day at 2 am. and that is what I use to set all my other clocks. So yes, one second a week would bug me

I have one also. A Seiko Coutura Radio Sync Solar.

 

[rvdummies]

​

RacerX-KEY makes an excellent point. Load up your truck and RV with what you expect to normally take with you (people, pets and a full tank of gas included) and then get to a truck stop with a scale. It'll cost you about $15, but will let you know exactly how much weight you're putting on you axles. The scales have 3 sections - one for your front axle, one for rear and one for your trailer. Compare the results with your max axle weight specs and max trailer weight and act accordingly. Also, you will loose traction the higher the PSI, especially with the weight distribution system.

 

[jadatis]

Found your tire 275/60R20 in E-load 123/120 loadindex, but check that.
Is maxload singleaxle 1550 kg/ 3417 lbs AT 80 psi

Made cold pressure axleloadcapacity list with build in maximum reserve, at wich comfort and gripp still acceptable.
For that I give 90% of calculated loadcapacity for max 160 kmph/ 99 mph.
Driving only 75 mph gives extra reserve, but still acceptable comfort.

Now you " ONLY " have to determine the axleloads in your use 99% accurate, and look them back in my made list.
But this is the most tricky part in it all, and your responcibility.


Gave also the pressures in between the 5 psi steps.
Then if 3000 lbs GAWR , as someone wrote is right 37.5 psi , make it 40 psi is enaugh, for maximum loaded ( not overloaded) axle.

The 50 psi you use now is enaugh for an axleload of almost 4000 lbs with all the reserves.

The real weight in your use is important for the needed tirepressure. So if you rear axle is overloaded, search back the overloaded axleweight .
And you dont need to do pre- or aftercalculations yourselfes, all reserves included in the list and per axle given.

Only for singleload axle , as you most likely also have behind ( 2 and not 4 tires on the axle)

Axleload/ cold psi
1749lbs/ 20,0 psi
1940lbs/ 22,5 psi
2129lbs/ 25,0 psi
2318lbs/ 27,5 psi
2506lbs/ 30,0 psi
2693lbs/ 32,5 psi
2879lbs/ 35,0 psi
3065lbs/ 37,5 psi
3250lbs/ 40,0 psi
3435lbs/ 42,5 psi
3618lbs/ 45,0 psi
3802lbs/ 47,5 psi
3985lbs/ 50,0 psi
4167lbs/ 52,5 psi
4349lbs/ 55,0 psi
4531lbs/ 57,5 psi
4712lbs/ 60,0 psi
4893lbs/ 62,5 psi
5074lbs/ 65,0 psi
5254lbs/ 67,5 psi
5434lbs/ 70,0 psi
5613lbs/ 72,5 psi
5793lbs/ 75,0 psi
5971lbs/ 77,5 psi
6150lbs/ 80,0 psi/ referencepressure

6328lbs/ 82,5 psi
6507lbs/ 85,0 psi
6684lbs/ 87,5 psi
6862lbs/ 90,0 psi/ sometimes also given maxcold

 

[Cajun Couple]

I ran 65psi cold in the 10 ply BFG's on my Expedition. This was front and rear because its a FX4 with the AWD feature from Ford. Tow/Haul mode puts it into the AWD mode so I'd rather keep the tire pressures the same. Weak point is the independent rear suspension instead of leaf springs. Our camper is heavy on the hitch weight so I ended up buying son in laws F250 diesel mostly to tow the camper with.