TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Tire Pressure and tire life expectancy

Discussion in 'Roadster' started by Sparrow, Feb 10, 2011.

  1. Sparrow

    Sparrow S105/ Roadster 189

    Joined:
    Dec 14, 2010
    Messages:
    566
    Location:
    Marietta, GA
    I was curious given the apparent fact that the Roadster tires wear out quickly, are there many people over inflating their tires to hopefully extend the life of their tires while also improving their driving range. Since most tire wear I have seen on other cars has been on the edges of the tire, maybe having a higher pressure in the tire will allow more even wear in the center too.
     
  2. Lancelac

    Lancelac 2010 Roadster Sport #690

    Joined:
    Nov 17, 2008
    Messages:
    156
    Location:
    Chicago
    I slightly overinflate, and had no problem with uneven wear. Stil, I am about to replace my summer tires (about 5000 miles on them), the rear because they are bald, the fronts because driving around in the city (and having such soft tires) has rewarded me with a bolt stuck into both of them. The bolts were in there for months without even slow loss of air pressure, but in the long term it'll cause a blowout, so I'm replacing them all.
     
  3. Talkredius

    Talkredius Member

    Joined:
    Jul 29, 2010
    Messages:
    230
    Location:
    Hueckelhoven, Germany
    #3 Talkredius, Feb 10, 2011
    Last edited: Feb 10, 2011
    assuming your tire pressure is in the spec range, the live time depends only on the way you drive and the rubber mixture of the tires. Heavy acceleration combined with twisty roads means max.fun but min. life time.
    low acceleration combined with straight highways means max. life time.
    If you over inflate your tires a little bit (as I do too) you'll get a lower roll resistance but you may loose some marginal grip. If you extremely over inflate your tires they are not flat any more but more like balls.
    This means lower roll resistance but also substantial loss of grip. And of course they will wear out more quickly, because they are only rolling on the edge of the "ball" in the middle of the tire.

    For drag races on (secured) tracks you reduce you pressure a lot, not for the grip but to get the tires more quickly to the right temperature and then get the max grip.
    Expect a life time of a week end or so.:eek:

    Never do this on normal roads, it is deadly dangerous.

    If the tires are worn out at the edges of the tire, left or right side of the tire, then something is wrong with alignment or camber.
     
  4. Sparrow

    Sparrow S105/ Roadster 189

    Joined:
    Dec 14, 2010
    Messages:
    566
    Location:
    Marietta, GA
    I got my 2008 Roadster used with 5500 miles on it and I have put an additional 1500 miles on it in the 2 months I have had it. The tires do not look worn to me at this time and I would like to maximize their remaining life. Having been the owner of some very underpowered EVs, the Solectria Force (0-60 in about 20 seconds), I have no trouble driving the Roadster sedately most of the time so I am already doing that to maximize my tire life.

    When I got the car, the tires were 36 front and 46 back, is that slightly overinflated or way overinflated? What are you running them at?
     
  5. Talkredius

    Talkredius Member

    Joined:
    Jul 29, 2010
    Messages:
    230
    Location:
    Hueckelhoven, Germany
    I always running my cars with max. pressure (spec) + 0.3 bar (+4,35 psi)
    The Roadster with 2.4 bar (34,8 psi) front and 3.1 bar (44,96 psi) rear.
    I would feel safe with 36 / 46.
    I guess the "ball effect" starts above 4 bar (58 psi), I'll ask my brother, owner of a tire shop, tomorrow (European time ;-) ) for more accurate datas
     
  6. n8te

    n8te Member

    Joined:
    Feb 18, 2010
    Messages:
    15
    I would adjust understeer tendency with adjusting the anti-roll bars and the camber, not the tire pressure.
     
  7. Alan

    Alan Member

    Joined:
    Sep 18, 2010
    Messages:
    248
    Location:
    UK
    As above, if you have adjustable suspension then adjusting the shocks and anti roll bars (covered in other threads) is the way to go.

    Just adjusting tire pressures will help though. To reduce the bumpy ride, you need lower tire pressures but to reduce understeer you need to increase the front tire pressure so to an extent you can not have both grip and comfort.

    Reducing rear tire pressure will be a win/win for you as it will lower understeer and improve the bumpy ride. I assume the lowest rear pressure you can have without the tire pressure monitoring getting upset is going to be 36psi (as above) so try that with say 30 at the front.

    You can drop the front pressure a bit more for a softer ride (and perhaps a better feel through the steering) but this reduces front end grip a bit so understeer will increase.

    Having owned several Lotus over the years, I have always found that the suspension settings / tire pressures are very sensitive to changes and it seems the same on the Tesla. A few psi change in tire pressure can make a big difference to how the car feels.
     
  8. AndrewBissell

    AndrewBissell Member

    Joined:
    Apr 16, 2009
    Messages:
    645
    A Tesla service person confirmed that 35 front 45 rear is safe and will extend range.
     
  9. Talkredius

    Talkredius Member

    Joined:
    Jul 29, 2010
    Messages:
    230
    Location:
    Hueckelhoven, Germany
    here as promised the more accurate datas :

    a) min pressure

    min. pressure (spec) - 0.5 bar (7.25 psi) is dangerous, you should never drive with such a low pressure. If the pressure drops to this point e.g because you got a bolt in your tire you may drive very carefully with low speed to the next garage nearby.
    For a longer distance you should stop the car and fix it. (Use the tire sealant kit or get a new tire or transport the car with a truck). Keep in mind, new rims are quite expensive, I know what I'm talking about:redface:

    b) max pressure

    The max. pressure is printed on your tire. That may differ from the recommended max. pressure in the manual. For my rear Hancock winter tires I found 3.4 bar (50 psi) as the max. pressure on the tire (see the attached picture)


    You may use a 20 % higher pressure as it is labeled on your tire but that is not recommended. If I would get into an accident not caused by me, in Germany the insurance company might pin some guilt on me, because the tire pressure was out of the tire specs. (If they can proof it)


    And, as Alan already mentioned, any significant change to the tire pressure may result in a different handling of the car. If you make some changes to the pressure, drive carefully the first few miles , don't start like a rocket :smile:
     

    Attached Files:

  10. Sparrow

    Sparrow S105/ Roadster 189

    Joined:
    Dec 14, 2010
    Messages:
    566
    Location:
    Marietta, GA
    Thanks for the input. I've found out that the car's tire sensors don't like pressures above 50psi for the rear tires. I'm guessing the front tires would be 40 psi maximum before the sensors give the warning.
     
  11. dwegmull

    dwegmull 2013 Model S 85

    Joined:
    Oct 8, 2009
    Messages:
    238
    Location:
    Redwood City, California
    My tires are at the default pressure from the day the car was delivered (a little over a year). Except for a four month "break" (car in shop following an accident), I drive it almost everyday and have accumulated over 6000 miles. I drive mostly on congested roads and suburban streets. I occasionally "put the pedal to the metal", mostly on highway on ramps. I do not race and rarely exceed 65MPH.
    My rear tires still have about half of their thread left. By half, I mean the amount left above the wear bars is equal to the bars' own thickness. I will probably have them replaced at my next annual service, in December. The front ones are barely used. I guess they will last 50% to 100% longer than the rear.
    I think driving on twisty roads has a significant impact on tire wear (added side stresses). The road surface on which you drive also impacts wear: a more abrasive surface such a rough concrete will claim more rubber than a softer asphalt. Of course, pot holes and other sharp impacts can't be good either!
     
  12. Nik

    Nik Dreaming no more :-(

    Joined:
    Jan 18, 2011
    Messages:
    244
    Location:
    Cambridge, UK
    These tyre lives seem very short to me - does anyone know if US tyres are made much softer that European ones? On a variety of FWD ICE cars, I typically get 30,000+ miles from the front tyres and 60,000 from the rears. Manfacturer's recommended pressures usually more like 32-34 PSI, IME.

    I don't have anything like the power of a roadster, and we don't have many concrete highways, but all the fuel savings from EVs are going to be spent on tyres if they don't last longer than that...
     
  13. Doug_G

    Doug_G Lead Moderator

    Joined:
    Apr 2, 2010
    Messages:
    15,852
    Location:
    Ottawa, Canada
    Roadster tires are made much softer than "European" ones, or North American ones for that matter, and probably get abused more. I get similar tire endurance on "ordinary" cars as you do.
     
  14. mpt

    mpt Electrics are back

    Joined:
    Oct 15, 2008
    Messages:
    1,629
    Location:
    Warren, New Jersey, United States
    Me too, I used to run the rears at 45 and found that on hot days the extra temp took them to 51 triggering a warning.

    I'm assuming that the max pressure on the sidewall is the 'cold' pressure as, even at 40psi cold they can hit 46 at speed.
     
  15. mpt

    mpt Electrics are back

    Joined:
    Oct 15, 2008
    Messages:
    1,629
    Location:
    Warren, New Jersey, United States
    Yes, we figured that on the BBC fud thread, with factory tyres the cost of wear exceeds the cost of fuel!
     
  16. Nik

    Nik Dreaming no more :-(

    Joined:
    Jan 18, 2011
    Messages:
    244
    Location:
    Cambridge, UK
    Yes - if you have to drive to a garage to inflate your tyres you should never travel more than half a mile or so.
     
  17. Lloyd

    Lloyd Active Member

    Joined:
    Jan 12, 2011
    Messages:
    4,885
    Location:
    San Luis Obispo, CA
    If you inflate with Nitrogen you will get much less variation with temperature. I keep a bottle for my cars and motorcycles.
     
  18. TEG

    TEG TMC Moderator

    Joined:
    Aug 20, 2006
    Messages:
    17,252
    Location:
    Silicon Valley
    #18 TEG, Feb 14, 2011
    Last edited: Feb 14, 2011
  19. Nik

    Nik Dreaming no more :-(

    Joined:
    Jan 18, 2011
    Messages:
    244
    Location:
    Cambridge, UK
    Have you got any hard info on that? I know it's not exactly exhaustive research, but the top 10 hits on Google don't exactly fill me with confidence that there's a lot of benefit to be had.
     
  20. Doug_G

    Doug_G Lead Moderator

    Joined:
    Apr 2, 2010
    Messages:
    15,852
    Location:
    Ottawa, Canada
    Variation with temperature - I really doubt it. Air is already 80% nitrogen.

    The purported benefit of nitrogen is very slightly slower leakage, e.g. 1.5 PSI per year. Not a big deal, especially if you check your tires occasionally - or have a tire pressure monitoring system.
     

Share This Page