[RudyF6]

Everybody has their opinion and stories, here's mine.

My car had 24,000 mi when I bought it and the OE Michelin ZP tires were decent. Worn evenly and nowhere near the wear bars yet. Noisy and stiff, wouldn't hold a line in a bumpy curve driven aggressively - didn't expect that. What really disturbed me though, they hydroplaned so bad I was scared to drive it in a steady rain! I chalked it up to the tires being farther worn than they looked, and I have snow tires mounted now which are far superior in every aspect.

Fast forward to a week ago or so, driving a loaner CTS with only 124 miles on Bridgestone run-flats. Same thing - fairly heavy rain and that thing scared me to death hydroplaning! 40mph on a 55mph secondary highway without skating all over the road. My ride home in my own car with snows on it was smooth and uneventful on the same road, same day. I honestly don't know who designed these tires or who spec'd them for our cars, but they must live in an extremely dry climate.

Are they all that bad? Is there a run-flat that's better rated for rain performance?

 

[Ranger]

How much tread was left on the "run flats"? Hydroplaning is usually caused by excessive tread wear leaving water nowhere to go.

 

[RudyF6]

About half tread on my tires, but the loaner I was driving was brand new - 124 miles.

 

[basscatt]

About half tread on my tires, but the loaner I was driving was brand new - 124 miles.

====================
a quick look at the tread design will tell you whether the tire will be good on wet pavement or not -

if there are no open channels from the center of the tread to the outside edge -
there is no easy path for the water to go and you WILL hydroplane -

 

[Submariner409]

Yup - "all season" tires are rain-better than performance tires and snows are even better. As posted, the easier the tire can move water out from the contact patch, the better it will act in rain. Worn tires will hydroplane much easier than new tires.

Cold tire pressure also affects hydroplaning and traction performance. Over-inflation wears the center of the tread - that tire will be harsh riding and hydroplane readily.

Read the manufacturer's ratings and the customer reviews in www.tirerack.com.

 

[dkozloski]

9X the square root of the tire pressure = the speed in knots at which the tire will hydroplane. This is the formula for aircraft tires. I would suspect the tire pressures were dropped in search of a softer ride with run flats.