Recently, I thought my suspension was showing premature wear. My Model S felt a little sloppy on anything but smooth new pavement.
The solution was very simple: I re-torqued the car's lug nuts. Even though I had done this two months ago, all but two of the car's 20 lug nuts were below spec, some taking nearly a quarter-turn. I don't think I was close to losing any of them, but apparently they were just loose enough to allow some wheel play.
Given the weight of the Model S and the forces generated by its impressive cornering, this should not come as a big surprise. On top of this, the roads in New England are in particularly bad shape this year due to an unusually cold winter. Moral of the story: re-torque your wheels often! Tesla does this as a matter of course whenever a car comes in for service. But if you have a wheel removed for any reason, the lug nuts should be re-torqued after 50 miles of driving. Many tire dealers require you to come back to have this done.
The easiest solution is to invest in a quality 1/2-inch torque wrench. There are plenty of decent ones on the market, but I'd be inclined to get the same one that the Tesla Rangers use:
Snap-on Industrial Brand CDI Torque 2503MFRPH 1/2-Inch Drive Adjustable Micrometer Torque Wrench, Torque Range 30 to 250-Foot Pounds - - Amazon.com
You'll also need a 21mm 1/2-inch-drive socket and a 4 or 6-inch socket extension. If you're not familiar with the procedure, have someone show you. It's not difficult and only takes about five minutes.
The standard torque setting for either size wheel is: 130 lb/ft or 175 Nm. (Note: This is not listed in the owners manual.) If you have your tires changed at a non-Tesla dealer, be sure to give them this torque spec. Chances are, they've never seen a torque spec this high before. It's also a good idea to request that they "hand-torque" the lug nuts.
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UPDATE
I would not have believed re-torquing would make such a difference without experiencing it first-hand. I've owned and maintained Ferraris in the past and never noticed this before. (The Ferrari torque spec is 40% lower than the Model S.) The difference, no doubt, is in the vehicle weight and the wheel diameter. These factors account for both the tendency for lug nuts to loosen, and the effect that "loose" lug nuts have on handling.
I'm running 21-inch wheels with Michelin Pilot Super Sport XL tires on my P85. Both the tendency for lug nuts to loosen and the subsequent effect on handling are probably magnified with the 21-inch wheels due to their diameter and the stiffer sidewall on the 21-inch tires. Even so, I would not hesitate to check 19-inch wheels regularly too.
The Model S is really a new category of car in terms of its combination of power, weight and low center-of-gravity. There have been few production automobiles that put such high lateral force on wheels and suspension.
UPDATE 2
Here we go again. It's barely two weeks since my last torque check. After a weekend of spirited driving in my P85, I checked the lug nuts again last night. Some of them took a 20-30 degree turn to get them back up to spec. For those with track experience in a high-horsepower car, this would not come as a big surprise. But the P85 pushes the envelope further with its flat torque curve, its weight, and the large diameter 21-inch wheels. Every P85 owner should own a torque wrench and check the lug nuts at least every 60 days.
The solution was very simple: I re-torqued the car's lug nuts. Even though I had done this two months ago, all but two of the car's 20 lug nuts were below spec, some taking nearly a quarter-turn. I don't think I was close to losing any of them, but apparently they were just loose enough to allow some wheel play.
Given the weight of the Model S and the forces generated by its impressive cornering, this should not come as a big surprise. On top of this, the roads in New England are in particularly bad shape this year due to an unusually cold winter. Moral of the story: re-torque your wheels often! Tesla does this as a matter of course whenever a car comes in for service. But if you have a wheel removed for any reason, the lug nuts should be re-torqued after 50 miles of driving. Many tire dealers require you to come back to have this done.
The easiest solution is to invest in a quality 1/2-inch torque wrench. There are plenty of decent ones on the market, but I'd be inclined to get the same one that the Tesla Rangers use:
Snap-on Industrial Brand CDI Torque 2503MFRPH 1/2-Inch Drive Adjustable Micrometer Torque Wrench, Torque Range 30 to 250-Foot Pounds - - Amazon.com
You'll also need a 21mm 1/2-inch-drive socket and a 4 or 6-inch socket extension. If you're not familiar with the procedure, have someone show you. It's not difficult and only takes about five minutes.
The standard torque setting for either size wheel is: 130 lb/ft or 175 Nm. (Note: This is not listed in the owners manual.) If you have your tires changed at a non-Tesla dealer, be sure to give them this torque spec. Chances are, they've never seen a torque spec this high before. It's also a good idea to request that they "hand-torque" the lug nuts.
-----------------
UPDATE
I would not have believed re-torquing would make such a difference without experiencing it first-hand. I've owned and maintained Ferraris in the past and never noticed this before. (The Ferrari torque spec is 40% lower than the Model S.) The difference, no doubt, is in the vehicle weight and the wheel diameter. These factors account for both the tendency for lug nuts to loosen, and the effect that "loose" lug nuts have on handling.
I'm running 21-inch wheels with Michelin Pilot Super Sport XL tires on my P85. Both the tendency for lug nuts to loosen and the subsequent effect on handling are probably magnified with the 21-inch wheels due to their diameter and the stiffer sidewall on the 21-inch tires. Even so, I would not hesitate to check 19-inch wheels regularly too.
The Model S is really a new category of car in terms of its combination of power, weight and low center-of-gravity. There have been few production automobiles that put such high lateral force on wheels and suspension.
UPDATE 2
Here we go again. It's barely two weeks since my last torque check. After a weekend of spirited driving in my P85, I checked the lug nuts again last night. Some of them took a 20-30 degree turn to get them back up to spec. For those with track experience in a high-horsepower car, this would not come as a big surprise. But the P85 pushes the envelope further with its flat torque curve, its weight, and the large diameter 21-inch wheels. Every P85 owner should own a torque wrench and check the lug nuts at least every 60 days.
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