Trailer Sway Due to Mismatched Tires

[twaynedaniel]

I tow a 25RB Reserve with a 2009 F150. I recently went to E load tires on the rear which were a little taller than the front tires. On our first trip after the new tires were installed, we experienced serious trailer sway. I couldn't drive over 55 and even at 55 it was white knuckle. As soon as we reached our campground, I drove the truck to a local Ford dealer in Pensacola since I figured the electronic sway control or stability control had stopped working. The Ford dealer diagnosed the problem as mismatched tires. Because the rear tires were larger than the front, the front tires were going 2.5 mph faster than the rears at 50 mph. This was causing the electronic stability control to continuously attempt to "correct" the problem by applying right side and left side brakes, hence causing the sway. The mechanic lowered the rear tires air pressure to 35 and upped the air pressure in the front tires to 45 (it made the front tires bigger and the rear tires smaller) so the tire sizes would be closer to the same. This helped and our return trip was much more enjoyable. l have 2 E tires on order for the front. If you are driving any of the newer F-series trucks with electronic stability control, beware of mismatched tires.

[mark5w]

I think that's good advice for any vehicle. Mismatched tires could be dangerous, esp when towing.

[johnboytoo]

I could see where not only the stability control would freak out,
but also the different side wall flex would have an impact too ...

good luck getting it straightened out !

[coastn]

Good input. Thank you!

[nachtmsk]

Excellent advice, thanks. There are so many variables that come into play when towing something. I had no idea when I started pulling our TT a year ago. I've learned a lot and I'm still learning.

[twaynedaniel]

I know what you mean. I've been driving my F150 for over 5 years and I never imagined slightly larger (or smaller) tires on the rear or front would cause such a problem. I am impressed with Ford's stability control system and that it is such a complicated and sensitive system. Live and learn.

[ewbldavis]

I can see this being an issue. Interesting how it messes up the computer

In relation, anyone with 4WD should already know you always keep same size on front & rear, or your 4WD will hang up like a bad transfer case or differential.

[twaynedaniel]

I was aware of that rule about 4wd but my F150 is 2wd so I did not realize there would be a problem. The Ford stability control definitely works. Thanks for your reply.

[ewbldavis]

Sorry...hope that didn't come accross wrong. Just an FYI - didn't mean that you overlooked anything. 2WD - that is rare, though! Especially here in the north!

[harley]

alot of people here in southrn Ontario have 2 wheel drives, I always have a 4x4 but very rarely take it out of 2 wheel drive, even in the winter. and a 2 wheel drive is better for towing but 4x sells better after the summer..

[twaynedaniel]

Wayne - yeah, I wanted a 2x f250 but there were none to be found in our area. The closest one was over 200 miles from my dealer, so I opted for 4x4. The dealer had approx. 35 f250's in stock, all 4x4. Super cabs are impossible to find as well, they are all crews. Oh well, I have it if I need it. Thanks.