Excessive rear tire wear.....?
 

Well my daily driver got another service, and another clean bill of health, however the shop said: "Only thing is, you'll want to replace those rear tires soon".
Really? I put on a new set last spring! However they probably have 20,000 or so miles on them. I know from previous threads that these cars are hard on rear tires. So is this typical of the amount of life I can expect? No biggie, but just curious.
I should add that I had the suspension and alignment set up to favor tire wear over handling.
And the shop also pointed out I was running them a bit under-inflated. I have been running them 27 psi F, 32 psi R. I have corrected it to the factory recommended 29 F, 36 R.
http://i286.photobucket.com/albums/l...pso0akovyo.jpg

http://i286.photobucket.com/albums/l...psfclgrzed.jpg

I use 3 sets of rear tires for every front set -- i.e., the fronts last 3 times as long.

-- peer

If you got 20k on rears, you're lucky.

Wait a minute....You've got 20,000 miles on those, they look that good and you're calling that excessive? Ha! :)

20k is a long time for rear tires

also the factory tire pressures are calculated to add understeer

if the tire is wearing evenly, it is not over or under inflated

Thanks for the responses!
I'm thinking too "conventionally" again. ;)
I'm used to my regular cars over the years where I can average 35,000-45,000 miles per set of tires! But none of them have been performance oriented. :D

It still looks as thought you may have some alignment issue maybe a small amount of rear tow passenger side

I had a set of Michelin 265/40/18 Pilot Sport 2 rear tires that lasted 8.000 Km (4.970 miles) - than they had 2-3 mm profile. :D Street use only. ;)

So i think everything is OK with your tires. ;)

Regards, Markus

^^ I agree ^^
In the first picture, the inner tread has worn much more than the outer....
Just compare it to the LHS tyre.

Echo that PW

I'll have the alignment checked again. ;)
I've had the lower control arm replaced on the driver's side, but the passenger's side is still original and beginning to make a little noise. That might be the difference that's causing the harder wear on that tire.
Thank you guys again for your input! :)

20K? I never got more than 8K miles from a set of rears on the street. You're good to go! :)

20k - that is pretty good.
My Potenzas are down to the wear bars at 13,000 miles! And I have enjoyed every on of them! Lots of canyon carving and blasts up Highway 1:)

You haven't even reached the wear bars yet.

I don't think my Hankook V12's had that deep a tread when brand new.

I'd keep driving those and check every 2k miles to see how they are holding up.

I guess if you get rain you may not want drive them past the wear bars.

My latest set are Bridgestone Potenzas...they are at 12k miles and need to be replaced. :rolleyes:

Wow, I guess I need to change the title to: Excessively Low Tire Wear! ;)

I go through two rears for every front, probably about 15-20k miles on each set of rears. I would advocate buying and storing the extra rears. Twice now I have had to replace all four because for some reason the 255 rear size is always getting discontinued. Since it is your DD, you might be able to get a few extra thousand miles if you go with a less performance oriented tire like High Performance or Performance instead of Ultra High or Max Performance.

I understood that is normal on a Box, as the rear tires have a bit of an angle to them. They don't ride straight up and down, so logic says they should wear on the inside much faster than the outside?

Mine wear the same way, the inner tread goes first. It can be misleading because the edges of the tire will look fine.

not too bad but you can get a little better wear with less toe in the rears.

Honestly, because its a high milage daily driver and I was at least partly aware of the tire wear issues of Boxsters, I put on a cheap set of tires last time. (Primewell Performance... house brand of Hibdon's Tires). They were $288 for the complete set installed including tax and lifetime hazard protection. I've been pleasantly surprised. They perform and ride extremely well, and apparently wear normal to above normal.
This way, it won't be traumatic to replace a pair of tires every 10 months or so. ;)

If you run a quality A/S tire with a 400 TW rating you may get 40k miles from them but the tradeoff is less glorious road grip in the canyons. For some this is a worthy trade but since I only put around 5k on my car annually I want MAX grip. I can't wait to put on a nice fresh set of sticky tires every year. Woohooo! :D

So what would the oem tire recommended pressure front and back? 99' 986

I am needing to replace my rears for the third time since I bought the car which had good tread all the way around. The fronts are still what the car came with and look fine. I've gotten no more than 8000 miles from a set of rears. It is always excessive wear on the inside. Ive read that this is normal alignment for best tire to road contact. But, I would be willing to trade off some of that in order to get reasonable tire wear.

-- So what would the oem tire recommended pressure front and back? 99' 986 --
I believe it's 29 front 36 rear. Many here vary these up or down a pound or two

-- ... I've gotten no more than 8000 miles from a set of rears... --
That is pretty bad at first thought but what kind of driving and what tires.
I replaced summer rears (wore as expected with neg. camber, insides most) after 25k miles of my miles. They came with the car from PO. I may have taken 5k to far only in the sense of wet road driving.
I'm 32k on the fronts, will replace this spring, and again probably 5k to far, again only wet roads

Both fronts and rears wear the insides the most (neg camber)
As stated above, if you took out the neg camber and went with harder tires, you could get longer life. BUT you would sacrifice handling - Whats the point

This is an example of excessive tire wear - down to the cord in ~250 miles.

Of course, 50 of those miles were spent pulling 1.4g in corners at 90-130mph. :)

http://i1114.photobucket.com/albums/...ps5j15edoj.jpg

Yikes! LOL!
Well they died doing what they love! ;)

my right tire after 2 track days. It was almost brand new!
http://986forum.com/forums/uploads01...1454538387.jpg

That's interesting. What would be the correct pressure if I wanted a little more oversteer?

I bumped my fronts up to 32psi. The don't scrub off as hard with a bit more air in them.

^^^
Increase front tire pressure and maybe decrease rear

I run 32 F and 34 R cold that ends up being around 36 & 38 hot

I see a very slight cold tear which is an indication that your tire was slightly over inflated. Hot tear is the opposite. I also see raised 'back' edges on the treads. Your shock rebound is incorrectly set (too fast) (or dead toasted). When the leading edges are raised it would be an indication that rebound is set too slow.

(we learn how to read tires in the pits when bored, really bored Jay)

I will put you in touch with my mates at Ohlins in Sweden. Please prepare $3,800 per wheel. This will save your tires on your upcoming and future track days :D

ps: I'd trade some tires regardless for a good track day, any days. Crappy Porsche suspension or not! Let's do this lolll

... and I think I'm reading your tire the other way around, correction; it would be the leading edge in that case. (tired, late, just came bk home, going 2sleep now, bye bye!)

Interesting stuff Fred.
tell us more

My suspension is bone stock. Im looking at putting a USA M030 in so I can still run in Street Stock

Sorry Jay, just took out the dogs for their walk. Nah mate, nothing wrong with the tire you posted.

PSI: Undefined really. Best to talk to your track-side 'aware' tire manufacturer for the baseline really. If you do regular track days then sadly you got to learn the visual difference between cold/hot tears so you can adjust your psi for both ambient temp & driving style through your days. Remember, you are more aggressive in the afternoon when the ambient temp (and track) is much hotter than cold morning. I often have a good 4~6psi difference between morning and afternoon session/race. 4psi is often just enough to ruin a tire within 3 hot laps (road rashes aren't kool loll).

Other factors also, tire compound, types, treaded/slicks, etc. Friggin science almost :/

Won't go in details RE rebound, compression, spring load, etc. Sure the Internet can teach you all about dialing your suspension. That only is you use adj coilovers (PS9?, Ohlins, etc etc).

ps: Got the M30 here, new, 4 years old only (ROW I think its called, forgot). Awesome kit (and affordable) for the street and occasional track day I've heard. Bit stiff over road bumps :D Go kart stuff man, you won't regret

tons of life left!

this is what happened to my supersports after a year of driving ( I usually drive about 10,000 km a year) very bad alignment >.<

I try to get an alignment one a year now, my current supersports are two years old now with lots of life left

http://986forum.com/forums/uploads01...1454558753.jpg


when the rear starts kicking out in the rain is when they need to be replaced ;) haha

I just bought a full set of 4 Sumitomo HRZlll's. I've read good things, so I'm hopeful :)

Wow, that's exactly what my previous set of tires looked like on this car! That's when I had the alignment adjusted to be more neutral.