Update:
GGR and others who try out these tires:
Increasing rear tire pressure definitely seems to be a further improvement.
Tire pressures are set prior to driving, before tire temperatures increase.
Front tires: 30lbs
Rear tires: 45lbs
<inserted update>
as of September 2012:
Front tires: 30-35lbs (psi)
Rear tires: 48lbs (psi)
<inserted update>
Small adjustments above 40lbs(psi) to the rear of the car are quite noticeable due to the majority of vehicle weight back there.
Next I am trying out a boost of front tires to 35lbs, still keeping 45lbs for rear tires.
Getting this narrowed down to what seems ideal.
-another update for March 9th:
Increase of front tire pressure does not change handling to a noticeable degree. Dropped front pressure back to 32lbs, keeping slightly above the 30lb spec due to the tread wear looking like the edges may be thinner than the middle part of the tread. This may be the way the tires were when new, I did not check them closely though when the car was new. This may make little or no difference at all, and does not seem to be a particular benefit from perspective of steering response.
Now for the rear tires we get great benefit from adjusting the tire pressure with these new tires.
Setting the rears at 40lbs on these new tires demonstrates very clearly the difference in steering response, even to the point that it feels like it may become over-steer at high speeds and cornering force. (very exciting really) Setting rear tire pressure to 45lbs tames this down quite a lot. My personal preference is somewhere between these two settings. It is really nice that the car can be tuned with rear tire pressure now.
Refined as of April 3rd:
My preference currently, and may be final settings for these tires on the car: (Overall steering feels very responsive, neutral and predictable)
Front tires: 30lbs
Rear tires: 43lbs - 45lbs
For a bit more response at low speeds (<40mph) try rear pressure at ~43lbs.
I like running the rear tires at 45lbs. Slightly higher tire pressure is good for higher driving speeds and longer range drives.
*** Late April updated again:
Hard cornering with power applied can start a wee bit of over-steer, but higher rear tire pressure moderates that and two actions are 100% effective at controlling this: Ease slightly off the accelerator or straighten the steering wheel just a bit.
Car is very exciting to drive. It has quick steering response, under-steer is no more!
Fun fun fun.
(I am so happy this car exists, and that I am alive now and able to own it!)
It is hard to believe I have put almost 5000 miles on these tires in less than 3 months! I still am very happy with my selection of these rear tires.
The tire tread on these is still standing tall. The original tires would be getting worn at this point, as I had to replace the originals before they hit 8000 miles, but these Michelin tires are doing great.
MichelinPilot Sport A/S Plus
They work great for sporty daily driving.
I had an interesting experience while driving on a 1200+ mile trip across the Southeast US.
Since I wanted to get the best range, I dialed up the rear tire pressure to 46lbs(psi) -rather like turning the volume on my "stereo" up to 11 right?
I then set off on the first part of my journey, from the Atlantic coast to stop in Augusta Georgia.
After charging a few hours, I set off on the next leg of my journey toward Atlanta. Shortly after getting on the Interstate, I heard a "gong" sound.
I was puzzled, and looking around, then heard it again. Finally I saw a message on the info display indicating a problem with tire pressure, so I took an exit and pulled over to investigate, then seeing a message that said the RH rear tire pressure was too high! I found this perfectly amazing, not because it happened, nor because the tire monitoring system on the roadster worked perfectly (I could not be happier about that), but instead, what impressed me was that the warning was exactly correct for the
not spec tires!
I am running rear tires that are non-spec for the roadster, and the pressure limits are very different from the Tesla spec tires. I must conclude the tires manufactured today have a RFID chip or metal strip device (inside the tire?!) that the car tire pressure monitor can "read" that indicates what the manufacturer tire pressure limits are for the mounted tires and then the car TPMS issues alarms based on that! The max pressure rating for the new tires is 51psi. Overpressure warning indicated 52psi! Perfect! Has anyone heard of this feature?
So why did I exceed the max pressure, and what did I do? The pressure increased because tire temperature increases when driven, and increasing the temperature of the air in the tires causes tire pressure to increase in proportion to temp. Also the ambient temperature increased in the middle of the day from the early morning start time. Another factor would be elevation was probably 350 feet above my starting near sea-level elevation.
What did I do? well it took a minute or two to get pulled over, get my tire pressure gauge out and verify pressures. It did match the TPMS indication of the car! I then just let a slight amount of air out of the tires, so the pressure was then 50psi. and continued on my journey with no other issues. After the trip was done I checked the pressures with tires cooled completely and they were back to my roadster preference of 45psi.
I will ask the Tesla service folks about the tire pressure monitoring system to confirm it really is this smart!
----
-Update Sept, 2012:
- at the annual service a couple of months ago I did ask about TPMS operation. Rangers indicate it is a proportional monitoring, in that if some pressure indication gets much higher than the other tires (above some percentage) it will issue an alarm.
So, based on that, I now have a reason to increase the front tire pressures as well as the rear, and I have done so.
Increased front psi does not seem to affect steering response at all, but should allow higher rear tire pressures without causing the TPMS alarm. 51psi is the max pressure for the Mich tires, that is measured cold (prior to driving). I now run at around 48psi in the rear, and around 35psi for the front -(original Yoko's still in fine condition at about 18,000 miles, and plenty of tread depth).
[-another update Oct, 2012: Based on my experience with this, the TPMS pressure alarm level for tire pressure "too high" is fixed, and not proportional, at least for the rear tires. It always goes off at 51psi. This needs to be adjustable or possibly disabled. I will go back to Rangers on this request.]
So for a further update, here is a picture of the drivers side Michelin (LH rear tire) after 10,000 miles of daily roadster sport driving:
I think the ~48psi or so for these tires on the Roadster is most appropriate. Lots of torque/load back there in perf. mode would likely be better handled with higher air pressure. The reduction in tendency to over-steer is a diminishing difference at this point, and I think the tires are nicely in the sweet zone for my daily zipping and zooming around the countryside.
In addition, I have had other (Roadster folks) drive my car with these tires, and they all agree that this is a winner. These tires cost less than the originals, weight is less, are quiet, they give a smoother ride, are lasting a lot longer, and they prove to be a drive-ability hop-up.
Changing the rear tires to this specification (and changing nothing else) provides very delightful, increased sporty steering response, in addition to the other benefits, to this awesome daily driver.
-enjoy.
