Help: new tires, sudden swaying

[Ritsui]

Sorry to put this in General, but I'm not sure if it's tires or suspension I'm dealing with yet.


Quickly: I had a local shop put new tires (Kelly AWR 245/75/16) on my 98 Sport after nearly five years on a pair of the same. Suddenly, the truck handles terribly. Top to bottom motion feels about the same as always and driving straight feels relatively normal, however any sharp turn creates drastic and dangerous side to side swaying which feels like the sway bar or shocks are simply gone. This most definitely did not occur before.


Details:
- The shop originally put on E rated tires by mistake. They felt really mushy even after they were inflated to the 80 psi they were rated for the next day (the guy who mounted them assumed C rated tires and only put 35 psi in), but I didn't test them with quick, sharp turning before the shop replaced them with the correct load rated tires a few days later.

- The issue isn't tire pressure or wheel mounting. Tires are at 46psi (rated 50) and the car tracks perfectly with no wobble or anything when going straight.

- The suspension is still stock, but I live in a mountain community and drive tight, winding roads all the time, so this is not something I wouldn't have noticed even if it happended very slowly (like shocks going bad).

- I drove almost five years on my first pair of the exact same tires (I was replace the Firestones the first month and Ford wouldn't pay for them , but that's another story...) without any trouble.


Whatever the reason, the car's handling has become extremely dangerous to the point of being nearly undrivable, overnight. So, I guess the question is: "WTF could they have done to my Ex?"

1) Kelly had a bad batch of tires with bad sidewalls (two sets)?

2) Low pressure on the E rated tires screwed up my wheels?

3) Something happened to my suspension when they first replaced the tires?


These are what comes to mind right off (and just writing this has given me some ideas on what to check), but I'd very much appreciate any input anyone or similar experience anyone else might have.


Thanks

 

[Alec]

Welcome!

46 psi in C tires is way too much, even though it's under the max pressure. Try somewhere around 32-34 psi.

Have you checked the swaybars to make sure they're still connected properly, and check the shocks too.

 

[AlaskanJack]

Hmm my buddy was having similar problems and had a 4x4 shop look at it. He was running 33x12.5 Mud Kings. The guy at the shop pushed on the side of the vehicle and not very hard and said look the side walls are flexing that's what is causing the swaying on the road.

My buddy showed it to me and you could see it with out pushing very hard. All 4 tires are doing it. Why I don't know my 35x12.5 Mud Kings don't do it. Weird!

 

[james t]

sounds like one of the tires possibly has a belt out of alignment. this is a tire defect.

 

[nak4af]

Hey Kurt!

Just figured it out! Your 35's are on 10" rims. Your sidewalls are extended out further which probably gives them more strength!

Does that sound right?

 

[Ritsui]

Thanks for all the replies.

- It's not tire pressure. Safari AWRs are rated 50psi and anywhere from 40 to 50 was just fine for the last set (on the highway).

- Yes, I checked and the swaybars and shocks are all still solidly connected.


The guy at the local shop says it's just worn shocks... but there's no way that's all of it. I can understand if the shocks are worn, new tires could account for some of the abrupt difference I'm feeling (tires grip more, shocks are loose, body sways more), but I can't imagine that's all there is to it.... notably considering the stock shocks have under 47K miles on them and only a few hundred of those have been off road.

sounds like one of the tires possibly has a belt out of alignment.

A tire defect was my first suspicion since I had no problems at all before replacing the tires, but I didn't think a problem with one tire could cause the overall "swimming" effect without any pulling or other noticeable problems. I also have little knowledge about the manufacturing process or how common such a thing would be (quite rare, I hope).

If that is the case, considering I felt the same problem with two sets of Safari AWRs (first E rated, now C rated) it's possible there is a whole bad batch of them.

 

[mhn3773]

i was driving a 2001? i think tahts the year tundra 4x4 ( work truck) and a tire went really low on air pressure rather rapidly just one and it gave me the same swimming effect it had enough air in the tire to keep the rim off the ground but when u pushed on the truck u could see the sidewall move

i know ur tires arent flat but just one tire can make the whole truck a very scary ride btw this was the left rear tires if that helps any

i think mabey try a little lower psi and also have u tried pushing on all four corners of ur X to see if the sidewall gives any?

 

[AlaskanJack]

Re: Hey Kurt!

Originally posted by nak4af
Just figured it out! Your 35's are on 10" rims. Your sidewalls are extended out further which probably gives them more strength!

Does that sound right?

Possibly Chris. I hadn't even considered that! Your on 8" rims with 12.5's. Ya know you may just have something there. Huh got me to thinking.

 

[Exp-Wi.]

balljoints ?

Some times balljoints can have a similar effect. The improved traction of new tires could make worn joints more noticable, maybe.

 

[Ritsui]

Update

Sorry for the five month bump, but I thought I'd fill in the gaps here for the future reference of anyone who ends up searching the forums as I have to solve a similar problem:

1) Not long after posting this thread, I replaced the factory shocks with Sensatracs (overdue anyway). Ride felt much better but the car was still unstable at higher speeds.

2) I replaced the Kelly tires with Revos. Incredible tires, but the swaying on bumps has gotten worse (probably mostly due to larger tires raising the center of gravity).


After reading a lot more posts here, I think Exp-Wi. may be right that improving traction is making the real problem (body roll, etc.) more noticable. When everything was loose, sudden changes in wind, pavement, etc. probably weren't causing the body sway I feel now... which is probably not a whole lot more than I've been reading that others experience.

Now, I'll be moving on to some other less expensive but more time consuming options starting with replacing the rear sway bar and both front and rear sway bar bushings, then moving on to ball joints, tie rods, radius arm bushings, etc as the time (not to metion money) becomes available.


Maniak/Ray: Please move this to "suspension" and feel free to remove "Help:" from the title... it sounds so desperate

 

[Ritsui]

Final explaination

Amazing neither a local shop nor the dealer could figure this out, but it was just a bit too much driving on a flat tire (which is what pushed me into buying new tires in the first place) which apparently put some play into my front swaybar end links. That combined with regular wear driving mountains all the time caused all the bushings (endlink and bar) to wear excessively. Replacing the front end links and bushings (energy suspension) and rear end links (stock from Ford) has completely removed the swaying.

 

[Ford_Racing_Guy]

glad to here you have that all taken care off,

its very satisfying once your vehicle is fixed isn't it