-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
19" and 21" Tire Wear (informal) Survey
- Thread starter lolachampcar
- Start date
-
- Tags
- Driving Dynamics Model S
Here is what I would do (swap=inside to outside, rotation=move tires to different position):
1. First rotation 1000-2000 miles to give every tire a chance on the drive axle early in it's life which will help set up an even wear pattern.
2. Check the tread depth from side to side occasionally and rotate/swap when either A) the inside has worn to 1/2 tread depth or B) the tires on one axle have worn down to 2/3 tread depth remaining (e.g. 1/3 worn).
3. If you found condition A, then swap the tires on the wheel so that the inside is outside. If you found condition B, then rotate in the normal manner.
4. Repeat steps two and three only use 1/3 rather than 2/3 as the "B" measure. The idea here is that you don't want to switch the tires from inside to outside more than necessary because there is a risk of damaging the tire every time it's mounted or demounted (and it's more expensive).
So if the tire starts with 9 mm and the wear bar is at 1.6 mm that leaves 7.4 mm of usable tread. 2/3 of 7.4 is 4.9 mm. So the first regular rotation should be when there are 6.5 mm left (4.9+1.6), the first swap should be when there are 5.3 mm total tread depth left on the inside of the tire ((7.4/2)+1.6), and the second regular rotation should be when there are 4 mm total tread depth left (2.4+1.6). The tires should be removed when there are 1.6 mm total tread depth left at the lowest point. (If you like /32nds then the numbers are 11/32 total tread depth, 9/32 usable tread, 8/32 first rotation, 7.5/32 first swap, 5/32 second rotation.) Be sure to check that your tires are really 9 mm (~11/32) because these are example numbers. Some high performance tires start with total tread depth as low as 5 mm.
Of course, you can rotate more frequently, but the 2/3-1/3 rotation method works well if there are no other mechanical issues. (The more frequent the rotations, the more mechanical issues are hidden--and likely the the higher the cost will be to fix them when you do find them.) It also keeps the tread depth of the tires even enough so that control in the wet is not a problem.
SCW-Greg
Active Member
Yeah great feedback Jerry. I was planning on rotating every 3 to 4000 miles, but checking the wear and changing on wheel makes great sense too.
Jerry,
So we finally baited in someone with first hand knowledge on the subject. Thank you. I was getting worried passing along second hand info from ten years ago
Are you in a position to tell us the source of your knowledge?
On a different note, do you feel it is camber alone that is driving the whole issue? If it is, why would there be such a large disparity between drivers? Could their styles be so different even when they are self described "normal" drivers?
So we finally baited in someone with first hand knowledge on the subject. Thank you. I was getting worried passing along second hand info from ten years ago
Are you in a position to tell us the source of your knowledge?On a different note, do you feel it is camber alone that is driving the whole issue? If it is, why would there be such a large disparity between drivers? Could their styles be so different even when they are self described "normal" drivers?
Jerry, Thanks. So, would you suggest swap on P+ every 2K miles to minimize tire wear? Any logic just to plan to do that? I am not a high mileage user as doing this would result in swap about every 2-3 months.
When you swap a tire do they remove it from the rim and turn it around? Also, does tire rotation always mean left front to left back for example (and left back goes to left front) or do you ever sway left front for right front or right rear? If Tesla won't do this for free at the service centers I wonder if the frequent rotations eats away at the savings from the tires lasting longer.
Last edited:
Camber is not considered to be a wearing alignment angle. However, it does amplify anything else that is even slightly out. The lower the profile of a tire the more it amplifies because the shorter the sidewall the less it will flex to compensate.
My understanding is that the suspension geometry of the Model S increases the amount of negative camber as the power applied increases (someone should do some videos of this to confirm). So accelerating at 15 kW (on the orange scale) tire wear will be more even than accelerating at 40 kW. Both of which could be described as "normal" driving. In addition there are the individual car differences in alignment. Road construction, superelevation, age, and aggregate materials also affect tire wear.
I looked at camber gain when I did my upper arms. I came up with .4 degrees of gain for 2" of lowering. I believe the change from Standard to Low is less than 2" of travel (and squat accelleration will occur most often at slow speeds thus while in Standard ride height).
http://www.lolachampcar.com/images/Tesla/Rear%20Geometry%20Model.pdf
http://www.lolachampcar.com/images/Tesla/Rear%20Geometry%20Model.pdf
mknox
Well-Known Member
Is there something specific to the Model S that requires more frequent tire rotations and/or the premature wear that is being reported? In the past, I only rotated tires maybe once a year or every 10 to 12,000 miles and never had any problems (at least that I was aware of). I would generally get 60,000 to 80,000 miles of life as well.
My Model S has a bit over 8,000 miles now, the tires have never been rotated and the tread depth looks good and even to my eye all around. I suppose I should pick up a tread depth gauge to be sure.
My Model S has a bit over 8,000 miles now, the tires have never been rotated and the tread depth looks good and even to my eye all around. I suppose I should pick up a tread depth gauge to be sure.
SCW-Greg
Active Member
The 21's (Conti's and Pilots) are directional tires, so you cannot rotate across sides, or you would be mounting a tire to rotate against its tread design. You can, as Jerry points out above, have the tire removed from the wheel and remounted (outside in) on the same wheel, and then be able to swap sides for more even wear.
I believe the 19" tires that come stock are also uni directional, but I could be wrong.
@DSM and Lola... The reason for the negative camber is to reduce natural oversteer, and encourage under steer. In emergency handling, or aggressive driving, most (novice) drivers get in to trouble quickly if a car begins to oversteer. The safer situation happens during under steering, as drivers naturally brake hard and stop if the don't get the behavior expected. Where in oversteer, people often panic (not understanding to steer into the turn) and the car often goes into 360 mode.
Edit: BMW and others use this same suspension set up. My father came back from Palm Springs, and unaware until nearly too late, that his 750iL rear tires (which can't be rotated, bigger rears than fronts), that he was driving on cords on the inside edge. Barely made the trip to Bend. He thought it an alignment issue, until BMW informed him, that this was normal. I don't recall the mileage he had though.
Last edited:
SCW-Greg,
The very high amounts of negative camber in the rear of current production cars is there for the reasons you point out and, more specifically, to comply with current stability control requirements. Here is the test section specifically designed for emergency maneuver testing in compliance with FMVSS 126.
Oversteering Test Maneuver
The required performance test uses a maneuver based on a modified 0.7 Hz sinusoidal steeringinput to assess ESC oversteering intervention performance. The maneuver, known as the 0.7 HzSine with Dwell maneuver, is depicted in Figure II*1. To ensure accurate, repeatable, andreproducible results, the performance test uses a steering machine to deliver the maneuver to thesteering wheel. Steering is initiated at 80.5 kmph with a variation of 1.6 kmph (50 mph + 1.0mph). Two series of tests are conducted: one with left*right steering maneuver and the other onewith right*left steering maneuver. Each series of tests begins with a test run with a moderatesteering wheel angle. The subsequent steering wheel angles are increased from test run*to*testrun in a series until a termination criterion is attained.
The very high amounts of negative camber in the rear of current production cars is there for the reasons you point out and, more specifically, to comply with current stability control requirements. Here is the test section specifically designed for emergency maneuver testing in compliance with FMVSS 126.
Oversteering Test Maneuver
The required performance test uses a maneuver based on a modified 0.7 Hz sinusoidal steeringinput to assess ESC oversteering intervention performance. The maneuver, known as the 0.7 HzSine with Dwell maneuver, is depicted in Figure II*1. To ensure accurate, repeatable, andreproducible results, the performance test uses a steering machine to deliver the maneuver to thesteering wheel. Steering is initiated at 80.5 kmph with a variation of 1.6 kmph (50 mph + 1.0mph). Two series of tests are conducted: one with left*right steering maneuver and the other onewith right*left steering maneuver. Each series of tests begins with a test run with a moderatesteering wheel angle. The subsequent steering wheel angles are increased from test run*to*testrun in a series until a termination criterion is attained.
mnx
2018 M3P
Do it, it's like 3$ at Canadian tire. Well worth it to know exactly how your tires are wearing.
I have the OEM Goodyear Eagle RS-A2 19" which are not very good tires, noisy and harsh. I have 3400+ miles on and the treads of the outer edge is gone for all 4 tires and I'm not sure why. I had the tires lower to 42 lbs for a couple of months to get a softer ride (supported by my local service manager). Did I under-inflate? Need inputs.. Very disappointed. I plan to get rotated at 6K miles but not sure if it changes anything.
In light of my tire issues, I did some research on the web and locate a very high rated tires, Michelin Pilot Sport A/S 3 just came out last month (replace the Michelin Pilot Sport A/S Plus). Michelin made a big splash and invited the media to test the tires and you can find many reviews on open web search, if interested. This is going to be my replacement tire.
In light of my tire issues, I did some research on the web and locate a very high rated tires, Michelin Pilot Sport A/S 3 just came out last month (replace the Michelin Pilot Sport A/S Plus). Michelin made a big splash and invited the media to test the tires and you can find many reviews on open web search, if interested. This is going to be my replacement tire.
Personally, I think 42 psi is too low. Mine are even across the tread at 6666.6 miles (yeah, It really read that today). It's heat, not pressure, that kills tires.
Could you really tell the difference in the ride? I can't.
Also, are you using a decent pressure gauge such as Longacre 50406 or 50404? Regardless of what you might read, cheap gauges--even if they are digital--are just cheap gauges and accuracy just isn't.
Also I've found that people who work on cars know little about tires other than that they are round and black.
@jerry333, thanks for asking about the gauge. I have the Michelin MN-12279 Digital Programmable Tire Gauge which is very reliable and accurate. I am a regular driver, not the race car driver type so the outer edge tread wear surprises me. It might be the 42psi did it to the tires. It's only <7% of manufacturing recommended and I did that for other cars too which didn't cause any damage. I wonder if you have 45psi on yours.
I'm so confused. Doesn't flipping the tire on the same wheel do the same thing? The tread is backwards in both situations...
Yes, it does. Jerry has also dispelled the idea that you can not spin the tire in the opposite direction so that means you can literally put it right back on the hub you took it off of. I'd always thought that was a no no so I put the left rear on the right rear and vise versa (to keep the tires spinning the same direction).
Wait, I'm dumb. If you flip the tire inside out AND rotate from right to left, then you still have the tire rolling the right direction.
I've never heard of anyone doing this before, but I may give it a shot. Assuming some of you have done it first. Any idea what a local tire shop would charge to do it for all 4 tires?
I've never heard of anyone doing this before, but I may give it a shot. Assuming some of you have done it first.
Any idea what a local tire shop would charge to do it for all 4 tires?Similar threads
