Saturday, September 19, 2020

DIY - Tire rotation. Recommend doing it every 5-6k miles.

I rotated the tires this morning. The rear tire depth was a hair above 7/32nd and the front tire depth was just under 9/32nd (not quite to 8/32nd) at 5100 miles. These tires at new come as 9/32nd per the specs at Tire Rack

Rear tires wear out much quicker even on an AWD

So the rear tires seem to wear out at approximately 1.5/32nd in 5000 miles and the front at 0.5/32nd in the same periods, or 3x faster in the rear. Since these tires are rated 400AA and should last ~40,000 miles when they reach 2/32nd and I seriously find that is going to be impossible to achieve.

They key for longevity is both correct pressure and frequent rotations. 

Front barely worn at 5K miles

I always set the pressure when outside low temperature changes more than 10F. For every 10F drop, tire pressures drop by 1 PSI. Same for increases. I maintain 42 PSI when cold. This means the car not been exposed to the sun, driven, and the tire temperature is the same as the average temperature of the day. Since summer is over around here, the daily temps have gone from 70-85F daily range to 45-65F. My garage stays at ~55F and in these morning, I set the pressures to 42PSI cold and measure using a very accurate gauge. I also fill with Nitrogen because it is easier for me. 

In winter where the outside temperature is say 5-20F and my garage stays at 40F, I adjust accordingly and fill the tires to 45 PSI with the assumption that being outside will drop the pressure by 3PSI upon the tires dropping in temperature from 40F to 10F, a 30F difference. This practice has helped me achieve maximum mpg, Wh/mi and longer tire life on all my cars.

As for rotations, Costco does my other cars tire rotation and rebalance every 5000-7000 miles depending on the car. But I cannot have them do my Tesla until I buy tires there. I happen to check the tire depths and was surprised to see such a difference between front and rears. Makes sense because even the AWD is a RWD most of the time.  

Since Tesla's are low maintenance cars and a shop does not need to see it for an oil change every 6 months, no one advices owners on tire rotations. This explains why at the super chargers I often see Model 3 with very bald rear tires and almost new front tires. Rotate your tires people!!!

Tire rotation is a super easy process, specially front to rear rotation without crisscross.

1. Put a chock the opposite side of the car that is not being worked on. e.g. front left is the jacking will be done on rear right.

Safety first

2. Remove the lug nut covers from the front and rear on one side of the car that is being worked on.

Pull out on any two consecutive sides to remove

3. Using a 21mm socket and T-bar loosen the torque of the lug nuts on both the front and rear wheels. They don't need to be loosened too much just broken free from their torque spec. This must be done in a star pattern.

Loosen Lug Nuts

4. Jack up the car using a jack pad and low profile floor jack from the front or rear, opposite end to where the wheel chocks were placed. The jack can be raised up enough that both tires on the side clear the ground.

Jacking up using adapter and low-profile jack

5. Put a jack stand and jack adapter under the other jack point for safety.

6. Remove the lug nuts and wheel from the front, remove the lug nuts and wheel from the rear. Swap the wheels around. Front to back, back to front.

7. Replace the lug nuts and tighten them in a star pattern as show. I prefer to torque them while the car is in the air. Easier to do on the rear because of the parking brake, harder in the front. The torque spec is 175Nm or 125 ft-lb.

Tighten to 125ft-lb using a star pattern.

8. Remove the jack stand, lower the car. Check and set the pressure.

Set the pressure to 42 PSI cold

9. Repeat procedure on the other side.

10. Done. The overall life of the tires has now been extended.

But there is one quick step. Letting the Tesla know that the tires have changed positions. If you have set the pressures correctly to exactly 42 PSI via an accurate gouge, then it is easy to just do a factory reset. 

11. Do a Relearn of the TPMS via Settings --> Service --> Reset TPMS Sensors 

Select Reset TPMS Sensors

12, Select a Factory Reset. The other options is for when you want select a new base for example if you are tracking and running lower pressures and do not want the TPMS warnings to come up for low pressure then "Learn new pressures" is applicable.

Select Factory Reset

13. Drive about 1 mile and hit a speed of >16 mph to wake up the TPMS transmitters in the wheels and the car will pick up the new locations of the sensors.