Tire life

[aboyandhisdog]

Okay, went to have an alignment done yesterday. I set the car up as "neutral" as we could get it with both toe and camber, front and rear. Near "0" on all for corners for toe and camber. Time will tell if tire wear improves. As for how it drives...very nice so far. No issues with cross winds, road crown or undulations in the tracks. For the way I drive, this seems like a very good set up. I guess if a guy drives very aggressively and really knows cars, he might want more of a "track" set up. I don't know for sure about that. I'm happy so far and, as I don't really drive near the limits or in the higher revs., all I can say is the car handles great and drives just like I would expect of a 911 (and I've had several). I'll be checking tire wear periodically and will report back.

Edit: The psi spec .on this car (997 C2) is 36 front, 42 rears. In my quest for even tire wear, I have landed on 42psi front, and 46 psi rears. With neutral camber and these higher psi's, I have very nice even tire wear across the tires.

[blueline]

Okay, went to have an alignment done yesterday. I set the car up as "neutral" as we could get it with both toe and camber, front and rear. Near "0" on all for corners for toe and camber. Time will tell if tire wear improves. As for how it drives...very nice so far. No issues with cross winds, road crown or undulations in the tracks. For the way I drive, this seems like a very good set up. I guess if a guy drives very aggressively and really knows cars, he might want more of a "track" set up. I don't know for sure about that. I'm happy so far and, as I don't really drive near the limits or in the higher revs., all I can say is the car handles great and drives just like I would expect of a 911 (and I've had several). I'll be checking tire wear periodically and will report back.

Edit: The psi spec .on this car (997 C2) is 36 front, 42 rears. In my quest for even tire wear, I have landed on 42psi front, and 46 psi rears. With neutral camber and these higher psi's, I have very nice even tire wear across the tires.

Thanks for that info Tom. That's excellent that handling and driveability is good - so important. Now for the next act, I hope that in 6-months or so you can report that tire wear has markedly improved too.

By the way, was the previous alignment from 3-years ago still where it was intended when you had it done back then? Also, with the new alignment at a neutral stance, were any substantial changes made to toe and/or camber from what it was? Just curious.

[aboyandhisdog]

You know, one thing that bugged me about the shop that did the alignment is that they didn't record the "before"...just the "after". I need to ask them about that. That said, the "after" figures were indeed more towards neutral than the figures from my previous alignment 3 years ago. If I had to guess (and that's pretty much all I do), I really don't think the alignment changed much if at all over time from my old alignment. That is to say, the car seems to have held the old alignment well over time (28k miles).

As to "was there much adjustment made vs. previously", front camber stayed almost the same, rear camber went a fair bit more neutral. Front toe went from 04' total toe to "0", and rear toe went from 21' total to 16' total toe. It gets confusing as the reports from the dealer were in degrees and minutes, and the one from the Indy is in decimals of degrees and minutes. In other words, the Indy says -0.5 degrees, whereas the dealer says -0 degrees 30'. I start to go nuts trying to make sense of this! And I'm told some shops report all of the measurements in mm!

Anyway, the Indy assures me that they tightened the car up appreciably towards "neutral" vs the prior alignment from the dealer. It drives great, but time will tell on the tire life. I don't mind at all experimenting with stuff like this if something positive might come from it. I enjoy learning about things like this.

[blueline]

You know, one thing that bugged me about the shop that did the alignment is that they didn't record the "before"...just the "after". I need to ask them about that. That said, the "after" figures were indeed more towards neutral than the figures from my previous alignment 3 years ago. If I had to guess (and that's pretty much all I do), I really don't think the alignment changed much if at all over time from my old alignment. That is to say, the car seems to have held the old alignment well over time (28k miles).

As to "was there much adjustment made vs. previously", front camber stayed almost the same, rear camber went a fair bit more neutral. Front toe went from 04' total toe to "0", and rear toe went from 21' total to 16' total toe. It gets confusing as the reports from the dealer were in degrees and minutes, and the one from the Indy is in decimals of degrees and minutes. In other words, the Indy says -0.5 degrees, whereas the dealer says -0 degrees 30'. I start to go nuts trying to make sense of this! And I'm told some shops report all of the measurements in mm!

Anyway, the Indy assures me that they tightened the car up appreciably towards "neutral" vs the prior alignment from the dealer. It drives great, but time will tell on the tire life. I don't mind at all experimenting with stuff like this if something positive might come from it. I enjoy learning about things like this.

Alignment specs drive me nuts too, so you're not alone. I know you keep good records so time will tell.

To be continued...

[Tom_N]

I can say from experience that a FWD hot hatch eats front tires! I also suspect that in our 911s that bit of lateral shift felt when accelerating out of a turn as the rear tires bite accounts for tire wear. As an aside I've watched GT3 racers on a high speed dogleg turn from above. Those rear ends positively jink just past the apex like no other car on the track.

[WillyDaP]

Tom,

I would just do what you have done in the past because in my 30+ years in the automotive business , you are getting quite decent mileage for a Porsche. With the weight and the need for a High Performance Tire , even if all season, you will get a compound that is never going to be on the super longevity scale. The insides usually wear the most, but like blue line mentioned most of the cars he has had had similar issues. I have never made it to 25K on rears tires with a single performance machine I have owned, so continue as before , but when you do replace the rears, get new fronts........tires of very distinct differences in age and tread depth are not the safest mode of transportation in my opinion.

[Ottomatic]

I know it's been 3 years, but how did the more neutral alignment work out for you, and how was tire life?

[aboyandhisdog]

I know it's been 3 years, but how did the more neutral alignment work out for you, and how was tire life?

I made some changes a couple of years ago (25,000 miles ago). I bought some 17" Fuchs and so achieved about ½" more in sidewall height which I just love - significantly better ride comfort. I bought some Nitto Motivos which are a high performance tire but not an "Ultra High Performance" tire like we are all told we need to run. They came with a 60k warranty. I went to 225/50/17 fronts, and 245/50/17 rears. My tread depth is now at 8/32 fronts, and 7/32 rears - slightly less on the inner edges, maybe 1/32 less due to the very slight negative camber. These tires new had a tread depth of 10/32" so I feel like, after 25k, they are wearing very well. At their current rate of wear, I would expect maybe 50k on the rears and 60k on the fronts, though I will no doubt replace them all at the same time in a couple of years.

As for the neutral alignment...I could not be happier! Understand that the shop still stays within factory specs, but at the most neutral range of those specs. The tires are now flat on the ground and wear evenly across the entire tread with only slightly more wear on the inner edge as mentioned previously. They track perfectly with no wandering due to road surface or cross wind, etc. This is the perfect set-up for me and the way I drive, but I guess if a guy was a very aggressive driver or spends much time on the track, you would want a more aggressive set-up. That said, I feel confident that this car could keep up with the best of them on the twisty roads.

I may be the only guy on the planet that goes from 18" wheels to 17" wheels instead of to 19" or even 20" wheels, but I have never liked the big wheels with the very low-profile tires. Our roads here in Colorado and not all that great, and so the low-profile tires are prone to damage and are not for me. Hope this helps - Tom.