Squrilly rear end in rain - new tires, bad wheel bearing

[insite]

Originally Posted by bmussatti

Well, here are a couple things to consider:

1) It will take about 200 miles for the tires to "scrub" in.

2) You are using non Porsche approved tires, so you should also expect less than optimum performance.

3) What is the air temp there now?

4) Check you tire pressures. Tire shops usually over inflate tires. You might get better grip with tire pressure adjustments.

certainly all good stuff to check, but if you had to slow down to 35mph to feel safe, your toe is tweaked. with excessive toe, your tires are either pointed toward each other or away from each other. when it rains, the decreased grip allows one or both tires to drag a bit rather than roll. this causes instability particularly in the rain. very uneasy feeling.

Are those tires Sumatomo? In either case my 2 cents.

When I was a lad, I had a tricked out Fiat X19, I was totally taken with the mid engine superiority design. So much so that I didn't respect the properties of wet pavement and took an unexpected spin on an off ramp; thank god no other cars were around. As it turned out, I was glad to learn my lesson in a car. Years later during my motorcycle phase, I learned that rain raises, oil droplets and other road deposits in the street. In short, pushing any vehicle with any tires in these conditions is a bad idea. Having said that, tire pressures, compounds used and tread design all contribute to performance. Making a great dry tire sacrifices wet performance and vise versa. Check out the tire rack website sometime, it has some great information regarding these principles. Of course if the geometry of the suspension is off everything I said means nothing. IMHO, a wheel bearing wouldn't cause this type of erratic behavior.

PS if you really want to experience your car, upgrade the rubber. My dealer thought he was doing me a big favor putting two new sumatumos on the car when I bought it. I ditched those tires a month later with a ton of tread on em and was glad I did.

[joshua6060]

Yeah Sumatomo HRTZ II's, I got what I could afford right now, Looking less than a month away from having the 75,000 mile check up so I know I'm going to take a hit on that so I got the 2 rear tires I could afford right now.....I wasn't pushing the car at any crazy speeds in the rain, I was driving 60 on the interstate. Felt unsafe and unsure so I slowed up to 35mph in the right lane then hit traffic 1/4 mile after that.

Originally Posted by joshua6060

Yeah Sumatomo HRTZ II's, I got what I could afford right now, Looking less than a month away from having the 75,000 mile check up so I know I'm going to take a hit on that so I got the 2 rear tires I could afford right now.....I wasn't pushing the car at any crazy speeds in the rain, I was driving 60 on the interstate. Felt unsafe and unsure so I slowed up to 35mph in the right lane then hit traffic 1/4 mile after that.

That doesn't sound like the rubber at all. I wasn't trying to put the tires down, i know all too well what it's like to be on a budget. i guess all I was saying is good rubber is a fantastic performance upgrade, I think as important as HP any day. Do you know if your car has ever been hit?

[joshua6060]

Yeah the Boxster is putting a hit on the wallet right now, so i'm just trying to watch the dollars when I know the hits are coming back to back.

I am unaware of the car ever being hit, I purchased it as a Certified Pre Owned Porshe and I checked the car fax report(I know that provides little assurance but thats the facts)

Originally Posted by joshua6060

Yeah the Boxster is putting a hit on the wallet right now, so i'm just trying to watch the dollars when I know the hits are coming back to back.

I am unaware of the car ever being hit, I purchased it as a Certified Pre Owned Porshe and I checked the car fax report(I know that provides little assurance but thats the facts)

If you have a warm garage and a powerful light you can do some self detective work. Look for any evidence of overspray on vents, molding, fender wells. Look across the paint for any tiny scratches that filler leaves behind. Look at the seams of the panels, make sure they have the same spacing, an example would be the hood line seams to the fender. Look for anything that is asymmetrical from one side to the other, compare the fender liners, and so fourth. The more you know the easier it may be to track down the issue, it's like being a detective, a process of elimination. Even if it has been hit, it's not the end of the world, but knowing it will assist you in deciding what to rule out. good luck, with patience and determination Ii know you will get it sorted out. My car originally had sport classics on it, some guy talked the dealer into swapping his turbo twists in a deal, I had to have my wheels trued and corrected as three were slightly bent, it's part of the reason I chromed them. You can sort out most any car all it takes is determination and a fat wallet.

[Benny986]

did you get the same size tire that you had before?

the sumis are not a great tire, but they are not horrific either, and you should be able to drive at least within your limits on them.

check pressures. if they are too high and to a lesser extent if they are too low. it will be a bit un-nerving.

and yes, they will take a little while to scrub in.

what kind of tires do you have up front? if you have a really grippy front tire, with these on the rear, that would exaggerate the issue.

FWIW, i recently put on new tires. the fronts got lots wider. and i didn't get my full set of spacers yet, so i was spaced way out up front, and not in the back, and my toe was still way off, in the rear. but the car drove just fine on my old tires so i didn't bother with the toe yet.

with the new tires. re01-r, which is a GREAT tire BTW. the back end was all kinds of unstable.

i put the full set of spacers on front and rear, and i changed the toe by 1/8 per side. its super stable now. before driving at 70+ was a little sketch and the back end felt like it was about to whip out at any time. i was at 1/16 out on each side, for a total of 1/8th out. which is A LOT! but i was playing with settings to get the back end to be able to come around for autox. I am now 1/8 total toe in.

follow the advice above, but just know that alignments make a big deal. and always try to have matched tires front and rear.

GL.
Benny