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Old 05-22-2014, 07:35 AM   #1
AussieCanadian
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Join Date: Feb 2014
Location: Calgary, Canada
Posts: 69
Rear end sway caused by tires F150 17" Rims

Hi all,

I wasn't sure where to post this (IE in towing or tires), however I took our trailer out last week for the first outing of summer '14, and had some significant rear end instability which felt a lot like trailer sway, but I believe maybe caused by the tires, and more specifically, the deflection of the sidewalls.

A few details - we recently upgraded our TV to a new 2014 F150 XLT 4x4 SCrew. The truck is a 5.0L with 3.73s and came fitted with factory "P" 17" wheels and tires. Trailer is a Keystone Hideout 24BHWE, 5800lbs (loaded) Towing hardware is a Reese WD hitch with the round bars. We never had this issue with our previous TV, but that vehicle (Ram 1500) had 20" wheels and P rated tires.

Some basics first - the receiver on my new TV is 0.5" higher from ground level than my old TV - this meant I was sitting slightly more nose up, and in addition, my WD bars were on the 2nd last chain link, and not as tensioned as they were with my old TV. As a trial, I have purchased a new drop shank to lower the ball 1" so the TV and trailer sit more level, and I can increased the tension on the WD bars. This MAY help, but I still believe this could be a tire issue.

SO why do I think this is tires? I drove our truck empty (no trailer) and simply by some slight left to right movement of the steering wheel at 60mph (100km/h in Canada) I could replicate the feeling of the rear end moving around - almost as if the tires were flexing laterally, a feeling which would be amplified if you through the trailer on the back. The max rated pressure of these tires is 44psi, and I have checked and filled to 42psi BEFORE I towed - hence I don't believe this is simply a tire pressure issue.

Has anyone had a similar experience before with the F150? As I mentioned, we never had this issue with our previous TV, and I am lost as to how to solve it. The new drop shank (and adjusting WD bars) may help, but is there anyone out there that has a F150 with the 17" rims (standard XLT wheels and tires) with similar issues? How did you solve it? Should I upgrade to 20" rims to reduce the lateral movement? Should I purchase new "LT" types tires rather than the "P" tires? We are planning a summer off this year and planning ~7500 kms (5,000mi) of combined towing over 3 months.... but with this issue and unstable feel, I am having serious concerns....

Hope to hear from other F150 owners out there...

Thanks!

AussieCanadian
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