There have been several previous discussions regarding
tires, trucks and trailers. I thought I had a good handle on what we were doing
but decided to investigate as we are planning some long trips. I was surprised
how far off my mental estimates were so I have decided to pass on what I have
learned.
The truck:
Ford 2003 F-350 Crew Cab, 4WD, 8’ box and
single rear tires. 6.8L diesel, 4.30 rear axle ratio with towing option.
Stock tires Firestone LT265/75/R16 Load range E,
3415# @ 80 PSI.
We have a minimalist 8” camper (875# empty)
The trailer:
Logan 4 horse slant
steel with two 6000# rated axles.
Stock tires 7.50-16LT Load Range E, 2780# @ 75
PSI.
On the way back from a recent ride we pulled into a road
side truck scale:
Front truck axle load: 4,550#
Rear truck axle load: 6,810#
Horse trailer load: 8,080#
Total weight: 19,440#
The specifications for the truck as listed in the owners’ manual:
Total combined weight: 20,000#
Max trailer weight: 12,500#
So going down the road with four horses and gear we were within 550# of
the gross combined weight limit of the truck and within 10# of the tire limits.
This was not acceptable to me because I want some safety factor. (My brother is
an owner/operator CDL cross country driver and he has told me the worst
accidents he comes across most often involves towed trailers of one sort or
another).
I went to the local Les Schwab and came up with a couple solutions:
There are now 8 lug rims available in 19.5” as
opposed to the stock 16”. (Be certain to also check the load rating of
the rims themselves. I saw some nice looking 16” alloy rims that had a
2200# load rating!)
We then mounted up some Toyo 245/70/R19.5, Load Range G,
4540# @ 110 PSI tires. The side walls are shorter and twice as thick which also
improves handling. (I also learned that load rating of tires can drop 5% to 15%
when used on a dually so keep that in mind).
We also added air bags to the rear suspension to lift the
rear end and steady the load side to side. It has a small air compressor and
controls/gages inside the truck to monitor/adjust the air pressure while on the
road.
The six year old trailer has freshly packed wheel bearings
and checked tires and brakes (both good until next year).
Unfortunately this all cost around $3500 but we have a noticeably steadier
ride (not that it ever felt bad). Ultimately what price do you put on safety
when you have 8 souls directly involved?
So the take away is: be certain you really know what you are doing (as
opposed to thinking you know). Base decisions on real measured data and
published recommendations!
Dean (with the eight of us (4M,4H) looking forward to competing in our
first full family ride at Chief Paulina this coming weekend)!
