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Possible to use some SUV-tires?

Discussion in 'Model S: Driving Dynamics' started by taraquin, Feb 24, 2014.

  1. taraquin

    taraquin Member

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    Hi, I`ve been thing about selling my RS-A2-tires and buy tires with better handling and lower rolling resistance. I see that a lot of SUV-tires have specs close to TMS. For instance I found the ContiEcoContact 5 with 235\55\R19. It has won numerous prices and no other tire that I know of can match it`s low rolling resistance. It also costs a bit less than for instance CSC5 and GY F1 AS2. The revs pr minute goes down from 729 to 692, is this too much?
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    SUV tires have lower rolling resistance because the diameter is larger. This makes the deflection of the tire as it enters and leaves the contact patch less. 5% is a lot when you are talking about the instantaneous torque of an electric motor. I wouldn't do it myself, but it's your car.
     
  3. yobigd20

    yobigd20 Well-Known Member

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    ? diameter of what? I don't see how that makes a difference. If one were to get a 245/45/R19 "SUV" tire it would have the same exact diameter as the OEM Goodyear's....
     
  4. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Well, not necessarily because the numbers are nominal. It would have the same interior dimensions because it requires a certain volume of air to carry the load, but SUV tires typically have deeper tread and often more crown area (more undertread and possibly and additional steel belt). However, the OP's tire was a 235/55R19 which does have a bigger diameter. I suspect the speed rating will be lower too.

    All that said what I was referring to was that SUV tire sizes are generally larger in diameter than passenger tire sizes, which is why SUV tires often show lower rolling resistance values--sometimes much lower.
     
  5. Arguably, the narrower contact patch of the 235 will improve fuel economy just like overinflating the 245's in terms of friction. We have not had access to any reliable rolling resistance numbers to help put a finer point on it, but I'd like to think that the benefit gained from the narrower tire would be offset by a small change in lateral stability. Either way, we're splitting hairs here.
     
  6. N4HHE

    N4HHE Member

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    Yes. While diameter of the tire can have something to do with its rolling resistance, LRR ratings are compared to other tires in the same size.

    My ML320 SUV wears 255/50-19's and MS wears 245/45-19. Sort of wish the MS wore the more common 255/50-19. A little wider. A little taller. A little more comfortable.
     
  7. taraquin

    taraquin Member

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