Currently I own two MX, a 2017 and 2018 both purchased new. Tesla has only made a small suspension change to the 2022 and newer MX and MS on the rear control arms but it didn't fix the tire wear issues but does allow a cheaper shim option to reduce the negative camber instead of a complete camber arm change. They probably won't do anything for the 2008 to 2021 models until they are forced to when the class action lawsuits for suspension issues are settled.
Buying adjustable rear camber arms for the 2021 and older S and X is the best way to eliminate the excessive rear tire wear and still use the acceleration at will without all the wear going to the inside edge of the tire. I'm in the process now of evaluating the best options to achieve my goals which is to retain the full use of the acceleration and increase range on the highway. You can get more life out of a set of tires without buying anything, just make sure you change the suspension settings to "Never" lower the air suspension automatically to "Low" which the pre-refresh models did by default in the settings (I'm not sure if this is an option on the software of the latest models as I didn't find it when test driving a 2024 MX which was in demo mode and may have hidden the screen with that option). Next is to set the performance to "Chill" until you want to accelerate the hardest, this reduces the HP and torque which transfers less weight to the rear of the car which further increases the negative camber producing more inner tire wear.
The other issue to consider is that all MXs have front CV axles that are at such a severe angle when in the "Medium" air suspension setting that you get drive line shake and shudder under moderate to hard acceleration in addition to premature leaks and wear in the CV bearings and race.
The way to stop the shake and shudder without purchasing a lowering link kit for the front ride height adjustment is to use the voice command before launching and say
"Set ride height to Low" or any other height and the computer will take care of it without going through the menu, however then you increase the rear tires inside wear by lowering. Before you purchase an MX you should review the Tesla
"Four Wheel Alignment Check And Adjust" page on their Service portal. You will need to create an account if you don't already have one to get to this link.
Model X Service Manual | Tesla Tesla may or may not follow all of these steps since the one time I had them perform an alignment the service center did not allow me to watch the work. Their alignment did nothing to improve the tire wear. They do it as quickly as possible and don't even give you the before and after alignment sheet unless you ask, then they only text a picture of the screen and refused to print it.
This year I decided to go to Tires Plus since they offered an annual alignment plan and I can watch them as they work. The problem is the alignment techs didn't follow the on screen instructions on their Hunter alignment equipment and got upset when I pointed this out then said they won't do another alignment (after 3 attempts at two locations) until I replace the front rearward control arm that had a small surface tear on a rubber bushing. I had to point out to them that they knew the tiny tear was there when they did the first 3 alignments but they still refused to realign until replaced. If anyone knows of an alignment shop that will do it right in central Florida please let me know.
Cars with air suspension have many more steps to perform before doing an alignment and the techs are under pressure to get the cars out as quickly as possible and don't do a thorough job.
A square tire/wheel fitment won't correct the issue at all but would make rotating easier to achieve longer tire life. For tire replacements I have been using Discount Tire and they will do a
"Flip Rotate" to remount any directional tire on the other side of the wheel so the inner wear is now on the outside edge then put the tire on the opposite side of the car which allows you to keep the staggered setup. I'm currently over 45,000 miles on my current set of Michelin Cross Climate 2 doing this.
The thing I recommend if you can find an alignment shop that you can verify will do all of the steps is to have them set the rear toe between positive 0.15 to 0.20 for the least rolling resistance which can decrease wear under acceleration but you will still get some.
I'm looking at the N2itive SX-2 camber arms, not the toe arms since Tesla's toe arms have adjustment and the HardRace adjustable rear arms but haven't decided yet.
