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

[joshua6060]

Hi Guys, its been a rough week for the Boxster, had a new battery installed and new HRTZ II Tires, when I picked up the Boxtster from the Tire shop, the guy told me that I had a bad rear wheel bearing and its possible that it could be a rear hub making the noise also. The noise isn't too loud, but slightly noticeable. I heard the noise before but I just assumed it was from the bald tires..... anyway since picking up the Boxster I had driven the car in the interstate 3 times, twice on clear days and 1 day when it rained, on the rainy day, I noticed that my rear end was very squirlly fortunately as I slowed down to a speed that felt much safer and less squirlly (35mph) as I hit traffic. Does anyone have any idea if the bad wheel bearing would cause my rear end to feel less stable in the rain? Certainly it can't be because of the tires because they are 3 days old...... Any comments would be greatly appreciated

[insite]

Originally Posted by joshua6060

Hi Guys, its been a rough week for the Boxster, had a new battery installed and new HRTZ II Tires, when I picked up the Boxtster from the Tire shop, the guy told me that I had a bad rear wheel bearing and its possible that it could be a rear hub making the noise also. The noise isn't too loud, but slightly noticeable. I heard the noise before but I just assumed it was from the bald tires..... anyway since picking up the Boxster I had driven the car in the interstate 3 times, twice on clear days and 1 day when it rained, on the rainy day, I noticed that my rear end was very squirlly fortunately as I slowed down to a speed that felt much safer and less squirlly (35mph) as I hit traffic. Does anyone have any idea if the bad wheel bearing would cause my rear end to feel less stable in the rain? Certainly it can't be because of the tires because they are 3 days old...... Any comments would be greatly appreciated

this is caused by excessive toe. you could have excessive toe either because the alignment is not proper or because a bad wheel bearing is allowing the toe setting at one or both wheels to change as you drive. wheel bearings are a common wear item on this car; i'd replace the bearing at the noisy wheel and get your alignment checked.

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.

[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?