I recently bought two new tires, I had the new tires put on the front and kept the old ones in back. I figured since I had front wheel drive that it would be better to have the newer ones up front. A little later I had my tires rotated and the front and back each have one of the newer tires. Ever since then, when ever I take a turn and there are ruts or bumps or holes in the road my rear end gets loose. Is this because of the fact I have tires that are slightly different in size because of tread wear. The new tires are the same size and make as the old tires. Or is something wrong with my rear suspension
I believe the second sentance answered your first.
Also, please remember what wear is - the loss of rubber, which changes the size.
Yer pal,
Satan
The size of the tire -whether 15 inches or 16 inches is not the size of the tire–its the size of the rim. The older tires are about 3 yrs older so there is quite a difference in actual tire size
If you haven’t already, you might want to check the air pressure in your tires. Sometimes those guys get a little carried away when they inflate your tires.
Very high pressure can cause them to bounce.
Peace,
mangeorge
I only know two things;
I know what I need to know
And
I know what I want to know
Mangeorge, 2000
I just said “The size of the tire -whether 15 inches or 16 inches is not the size of the tire–its the size of the rim. The older tires are about 3 yrs older so there is quite a difference in actual tire size”
I know that didn’t make sense–Im saying because of the loss of rubber my tires are different. in tread and in the tires actual size as in 225/55/16 or however they size them
Thanks for the advice Mangeorge. Oddly enough when I got my car back after the new tires were put on I checked the tire pressure and it was around 20psi. The tires should be around 32psi
My guess would be the shocks are worn. Your rear tires will always travel a different amount with turns and all, unless you live in Kansas. Don’t run 13 and 15 inch tires with a posi-trac rear end of course, but I have never had a problem with normal tire wear causing handling problems in the rear.
A point in every direction is like no point at all
Thanks for the advice Mangeorge. Oddly enough when I got my car back after the new tires were put on I checked the tire pressure and it was around 20psi. The tires should be around 32psi. I have checked the tire pressure every week since I noticed the problem and its where it should be
What does it mean for the rear end to be ‘loose’?
From what I understand, all the tires connected through differentials should have the same exact outside diameter, to within 1/4 inch or so. Otherwise the wheels turn at different speeds and put stress on the differential gears. In your case, the two front tires should have the same outside diameter, which means same size AND reasonably similar age.
I have no idea why it affects the rear end though…
scr4 what i meant by loose end is that when i turn and hit a rut in the road the rearend of the car doesnt follow the correct path. If you take a corner at 80 mph your rear end will most likely get loose and continue to travel in opposite directions that your steering wheel is turned. My rear end is doing it at 25 mph
First I’d get the two newest tires up front. That is a safety thing.
Your problem may be a broken belt. That usually comes with a thumping sound. In the worst cases you may feel the thump.
You should make sure the tire pressure is correct.
Then your tortion bar may be broken. It’s also known as a anti sway bar.
I doubt that it would do it but make sure your lug nuts are tight.
See your mechanic is the safe way to see that everything is allright. 
good luck
My first impression would be worn struts/shocks. Push down hard on each corner of the car. If it bounces more than once replace both struts on that end of the car.
Next guess would be a broken sway or panhard bar link. Look underneath.
WTF?
They did it wrong. Bias tires are rotated LF<>RR, LR<>RF. Radials: LF<>LR, RF<>RR (actually, radial construction is now good enough to use the criss cross rotation, if you want). Always buy tires in pairs and to keep them together on the same axle.
justwannano said “First I’d get the two newest tires up front. That is a safety thing.
Your problem may be a broken belt. That usually comes with a thumping sound. In the worst cases you may feel the thump.”
Well I would keep both tires up front but because I have this lifetime warranty(free balance, rotation, road hazard) I have to keep my tires rotated. If Merchants realizes I hadn’t been proprerly rotating my tires my warranty is void. It’s already helped me, after I got my tires rotated I got a flat tire and they fixed it for free and balanced for free and some other stuff. Tire pressure is correct. My belt is fine and the tires aren’t cupped.
pmh said “My first impression would be worn struts/shocks. Push down hard on each corner of the car. If it bounces more than once replace both struts on that end of the car.
Next guess would be a broken sway or panhard bar link. Look underneath.”
My suspension seems to be fine, I tried your suggestion and it doesnt bounce at all. The car goes down and goes right back up. I looked underneath and everything seems to be tip top. When I got my tires rotated I have one of the new tires RR and the other FL.
I would guess they did not put the nuts on tight enough. That causes a wobble. Its not pretty when the nuts come off later. You might ask them to check those.
Sometimes the air gun doesn’t tighten enough.
Some idiot above posted:
That’s for 4WD. Bias on non-4WD go LF>LR>RF>RR>LF. I should probably cut him some slack though. It’s been ten years since he’s even seen a bias tire.
siva, I still recommend you get those tires back on the same axle. Do it yourself and Merchant doesn’t even have to know. If there is any difference in traction between the two pairs, this should fix it.
It may be caused by the front tires pulling unevenly. Checked tranny fluid lately?
Have you removed a bunch of junk from the trunk? Less weight means less traction.
I don’t think it has anything to do w/ the lug nuts, but you should check them anyway (especially if you have alloy wheels). They should be re-torqued <b>by hand</b> every 25 miles until the reading doesn’t change any time a wheel has been removed.
Hmm,… that last sentence is ambiguous.
Any time a wheel has been removed, the lug nuts should be re-torqued, by hand, using a torque wrench. This procedure should be repeated every 25 miles until the torque reading doesn’t change from one time to the next.