Significant hydroplaning, excessive tire wear, rear tail "wag"


2005 C2S - 75000 miles
305/30ZR19 rears
245/35ZR19 fronts
It's a daily driver.
I'm not reckless but I do drive it hard but I wouldn't have guessed "that hard" to account for the "premature" tire wear. I never spin the rear tires.
I experience rear end tail "wag" when going over road defects. Seems like a pure side-to-side, lateral movement of rear end with not much up-and-down component, or rotational around long axis.
Because there's not as much middle-of-the-tire wear, I decided just today to take the pressures up to 37/43 psi "cold". I had been running about 33/38.

-17 months ago - alignment at indy Porsche shop to correct excessive inner treadwear; see embedded alignment values
.
-13 months ago - new Bridgestone S-04s on rear due to unfixable hole
-6 months ago - new Michelin PS4S tires (current miles 5248); rear S-04s only lasted 3915 miles; see embedded current tread depth values (in 32nds)

-couple of days ago - after no rain for months, rain; scary rear end hydroplane at 70 mph over suddenly appearing visible ponding

Are any/all of the symptoms connected?
What accounts for excessive tire wear on both sets of tires?
What accounts for the rear end "wag"? Is there a way to isolate the exact (suspension) parts that need to be refreshed?
What alignment specs contribute to resisting rear tire hydroplaning?
Can more camber on my setup resist hydroplaning? (At the expense of uneven tire wear, of course)

I know the biggest help for hydroplaning will be new tires; how can I help new rear tires to last longer? How can the vehicle be aligned to better resist hydroplaning as the tires wear?

 

Given enough standing water any car/tire can hydroplane. Especially wide tires...

 

If im reading your alignment otes correctly your toe on each corner is still .22?

mike

 

Yes - 0.22 deg toe-in at all corners.
Whatcha thinking , Mike?

 

thats on the outer limit of Porsche recommendations. The closer to zero toe the less edges will wear. .05 or so should help with that

mike

 

 

Btw analyzing your tread depth chart it doesn't look too bad.

the fronts are like new and the rears are a bit more than half used up. My rears go a max of about 10k miles. Fronts go twice that. Thats not uncommon for these cars. Keep in mind the 30k mile tread life warranty goes out the window on swaggered tires that cant be cross rotated.

mike

 

Thanks for uploading your alignment values. I'm running 10 mm wider front and rear. Do you think that is contributing to the excessive tire wear and the other things I've mentioned?

I would love to get 10000 miles. The current rears are within 1/32nd of being shot - that's about only 6000 miles total, if I've figured right.

 

I understand that I wouldn't likely get 30k but only getting about 6k? Even if I could rotate them, I'm barely getting to the point where most people are rotating them for the first time. It's just frustrating (and a bit expensive) to replace rears so often. And I really don't think I drive like a maniac to say that it's my driving habits that are contributing to the excessive wear.

For those that are getting 10000 miles or better on the rears, are you running closer to 0 toe-in?

 

 

Is that 0.5 total camber? Or, per side?

 

 

Here's the tire wear history and the alignment settings I'm running on my silver car in case it helps with additional data points. That rear tire life you're seeing is crazy low.

Tire history from my maintenance records on my wife's 05 997.1 C2S are:

• 49,800 miles - installed Nitto Invo
• 62,900 miles - installed 4 Hankook Ventus evo2 (Nitto's lasted 13,000 miles which is why we decided to look at something different for the way she uses and drives her car). I kept the front Invos to use on my car when I wore out the set that was currently installed
• 86,332 - installed 2nd set of rear Hankooks (set 1 lasted 23,432)
• 103,000 - current mileage reading and not worn out yet - this puts the front mileage at 40,100 and the 2nd set of rears at 16,668. Looks like they'll probably make it into the low 20,000s as well.

On my silver car, which is driven like it's stolen pretty much every time it leaves the garage and has about 150 more HP than a stock C2S because of the supercharger, I run the Nitto Invos for the extra grip.

• 35,900 installed 4 Nitto Invos #1 on Champion RS171 wheels
• 47,700 installed new ADV1 wheels with another new set of Invos #2 (original Invos still good) - sold the ADV wheels with set #2 at 49,000 miles and put the Champions back on
• 53,000 installed new Forgeline wheels with another set of Nitto Invos #3

Champions still have set #1 on them - rears are about done - fronts are good for another set of rears. Mileage on that set (53,000 - 35,900 - 1,300 deduction for ADV time from odometer) is 15,800

Silver car has a full Stage 2 race suspension (Bilstein damptonic coilovers, monoball top mounts, LCA, toe steer kits, camber locks, etc) and is corner balanced and running the GT3 alignment settings below. Alignment and corner balance was done on 4/16/2014 at 42,000 miles and hasn't needed to be adjusted since - probably because there's aren't any rubber bushings left to wear and everything is locked down tight.

 

Pete - That's what I'm talking about - my alignment values just don't seem so excessive as to "eat" a tire. What could explain the extremely short life? Could a broken or worn suspension component contribute? (But then why both sides equally excessively wearing?) Which one to focus on?

Do you have your wife's car's alignment values?