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19" and 21" Tire Wear (informal) Survey
- Thread starter lolachampcar
- Start date
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- Tags
- Driving Dynamics Model S
youlikeadajuice
P 9130
Brought my car in to the Springfield Service Center and they checked my alignment, below are the results. They did the camber bolt replacement during this visit. The Goodyear 19s are pretty worn on the inside shoulder after 21,000 miles, I think I may get a few thousand more miles before I need new tires.
It appears they did. From -1.2 to -1.7 on left and from -1.4 to -1.8 on right. They brought the toe more into line which is better, though.
youlikeadajuice
P 9130
That was my take too, I was hoping since the toe was corrected I'll see better wear. If I continue to see really bad wear, I'll have them reduce the camber.
toe causes wear. camber causes the wear to be focused on the inside edge. they took a little toe out but they put a lot of camber in. IMO you went backwards but then that is just MO.
youlikeadajuice
P 9130
Gotcha. From the comments upthread I thought the negative camber was ok as long as the toe was in check...I guess I'll definitely be requesting less negative camber next time. Thanks for the info!
There is a difference of opinion on the camber subject.
All I can do is speak from my personal experience which is-
(1) Negative camber is used more and more by OEMs to get past FMVSS-126 which are the mandated stability control requirements. Specifically, there is an emergency maneuver portion that requires the car to survive a violent steering wheel input regime (input, reverse input, pause, return to center). Having the rear of the car "roll onto" more contact patch gives a mechanical method to survive this test.
(2) We can assume that the coil spring equipped MS passes this test and rear camber values as low as -1 degree (or less, I do not remember the exact acceptable camber range) are perfectly acceptable even though the coil cars have a higher Center of Gravity (CoG).
(3) Air cars ride at a lower ride height. Modern suspensions have camber gain which means negative camber increases as the suspension compresses. Coil and air cars have the exact same suspension geometry in the rear. Add all of this up and you have air cars which have more camber than coil cars. This is done for convenience so as to only have one set of rear suspension as the extra camber in air cars is not required for stability. See #2 above.
(4) Many of my previous ICE have had high rear negative camber and they all tear up tires. I typically insist on leas than one degree of negative camber in the rear of my cars if they are to be driven many miles. I was able to achieve -1.2 on my MS so I combined that result with as little toe as possible to maximize rear tire life (my P+ is my daily driver). Near zero rear toe also significantly improved my range.
In summary, MS with air carries too much rear camber. Combine this with toe and your tires will wear on the inside shoulder.
In closing, unless you are well versed in these issues, it is unlikely most owners will be crawling on the ground checking out the inner most inch of their rear tires. Thus, there is a high likelihood that the tires will reach cord and even deflate. There is also the much less likely chance of a catastrophic deflation at speed. This does not seem to be a huge issue as there are not reports of a significant number of blow outs on the highway due to corded tires. This may change as the fleet ages.
Please watch your rears.
All I can do is speak from my personal experience which is-
(1) Negative camber is used more and more by OEMs to get past FMVSS-126 which are the mandated stability control requirements. Specifically, there is an emergency maneuver portion that requires the car to survive a violent steering wheel input regime (input, reverse input, pause, return to center). Having the rear of the car "roll onto" more contact patch gives a mechanical method to survive this test.
(2) We can assume that the coil spring equipped MS passes this test and rear camber values as low as -1 degree (or less, I do not remember the exact acceptable camber range) are perfectly acceptable even though the coil cars have a higher Center of Gravity (CoG).
(3) Air cars ride at a lower ride height. Modern suspensions have camber gain which means negative camber increases as the suspension compresses. Coil and air cars have the exact same suspension geometry in the rear. Add all of this up and you have air cars which have more camber than coil cars. This is done for convenience so as to only have one set of rear suspension as the extra camber in air cars is not required for stability. See #2 above.
(4) Many of my previous ICE have had high rear negative camber and they all tear up tires. I typically insist on leas than one degree of negative camber in the rear of my cars if they are to be driven many miles. I was able to achieve -1.2 on my MS so I combined that result with as little toe as possible to maximize rear tire life (my P+ is my daily driver). Near zero rear toe also significantly improved my range.
In summary, MS with air carries too much rear camber. Combine this with toe and your tires will wear on the inside shoulder.
In closing, unless you are well versed in these issues, it is unlikely most owners will be crawling on the ground checking out the inner most inch of their rear tires. Thus, there is a high likelihood that the tires will reach cord and even deflate. There is also the much less likely chance of a catastrophic deflation at speed. This does not seem to be a huge issue as there are not reports of a significant number of blow outs on the highway due to corded tires. This may change as the fleet ages.
Please watch your rears.
UberEV1
Member
Lolachampcar, thank you for gathering this data! Just measured mine today:
S85, delivered Aug-13, 19" standard wheels with Michelin Primacy
Current mileage: 5650 miles
Measured tread depth in outer and inner grooves
LF RF LR RR
Outside 0.26" 0.25" 0.24" 0.24"
Inside 0.26" 0.26" 0.24" 0.24"
Appears uniform; confirms rear wearing a bit faster than fronts (assuming due to regen on rear wheels).
Looking forward to any insight from data consilidation.
Thanks again!
S85, delivered Aug-13, 19" standard wheels with Michelin Primacy
Current mileage: 5650 miles
Measured tread depth in outer and inner grooves
LF RF LR RR
Outside 0.26" 0.25" 0.24" 0.24"
Inside 0.26" 0.26" 0.24" 0.24"
Appears uniform; confirms rear wearing a bit faster than fronts (assuming due to regen on rear wheels).
Looking forward to any insight from data consilidation.
Thanks again!
Owner
Active Member
As some of you may have read my other threads about my two recent tire blow outs, I am taking the time to try to understand camber, toe etc…. Tesla did tell me the following alignment was "normal". These numbers were provided by a third party very well respected mechanic who was quite shocked. Comments please!
The front look fine. The rear does not.
Have the SC install the new camber bolts and they will be able to get some of the neg camber out. Probably end up around -1.6 or so, which is still a lot but will help tremendously.
your biggest issue is that you have massive toe-out in the rear which will shred the tires. The SC can adjust that to a slight toe-in.
I had my alignment (incl camber bolts) done under warranty.
Have the SC install the new camber bolts and they will be able to get some of the neg camber out. Probably end up around -1.6 or so, which is still a lot but will help tremendously.
your biggest issue is that you have massive toe-out in the rear which will shred the tires. The SC can adjust that to a slight toe-in.
I had my alignment (incl camber bolts) done under warranty.
Who at Tesla told you that was normal? According to Tesla's own specs, the rear of that car is far out of alignment - as noted, the toe out in the rear is horrible, and the negative camber will amplify that. Looks like you'd be a good candidate for the camber bolts, and the toe links need to be adjusted to zero out the toe
Owner
Active Member
My service advisor insisted that this was "normal". I gave the valet a copy of this printout and a picture of the blown out tire too.
I'm looking at the first service report and I did get "New Bolt for Rear Camber Correction". I do not see any explicit note about toe links being adjusted although there is a vanilla line item for "wheel alignment service".
I'm looking at the first service report and I did get "New Bolt for Rear Camber Correction". I do not see any explicit note about toe links being adjusted although there is a vanilla line item for "wheel alignment service".
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Maybe he meant that it is normal for the MS to be WAAAYYYY out of alignment specs lol
For reference, near zero toe in on the rear of the car will improve range but at the expense of the car's willingness to follow road imperfections at highway speeds. A little more toe in improves stability at the expense of range. If I remember correctly, near zero for me was less than .1 in and "a little more" was about .4 in total.
I have close to 10K miles on my S. I have minimal tire wear on the OEM Michelins that I switched out at about 7,500 miles for Sottozeros for winter driving. This winter has been tough on our roads, so after several pot hole hits I took the S in for the first alignment at the TM recommended shop: Running 21" wheels
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Owner
Active Member
My original non-Tesla mechanic was appalled also at this, and decided to give Tesla service a call himself….
I'm not one to find fires in every issue but I've not seen another car with so many toe out alignment sheets before. I really hope this is a "coming out of the factory" issue and not a "happening on the road" issue as it is reasonably easy to fix issues with jigs at the production level.
