Stock rear SL rim - how wide of a tire?

  • The one thing about speedometer calculations that everyone will understand but usually doesn't consider when comparing old vs new tires is this. Take a typical tire that is worn out and requiring a replacement. That tire has worn down to a tread depth of say 2/32" of tread. The new replacement tire of the same size comes from the factory with 11/32" of tread. So when you compare the overall tire heights, the new tire will actually be taller by over half an inch. (11/32" - 2/32" = 9/32" TIMES 2 for a diameter difference of 18/32" or .5625")

    Nobody gets outta here ALIVE

  • I have about 5000 miles on it with no problems except the speedo is off a little, I usually always watch the speed on the gps when I'm driving

    I cant recall ever watching the speedometer, I usually just flow at my own pace, which if the right song comes on, might be an extremely fast pace

  • I cant recall ever watching the speedometer, I usually just flow at my own pace, which if the right song comes on, might be an extremely fast pace


    What's the point of watching the speedometer? When the cop that pulled you over asks, 'Do you know how fast you were going?', there is no answer that avoids a ticket. I've tried them all.

    Remember folks - this isn't a rehearsal, this is The Show!8)

  • I have about 5000 miles on it with no problems except the speedo is off a little, I usually always watch the speed on the gps when I'm driving

    Count yourself lucky, the stock wheel is 9" so you have over an inch undersized which could be catastrophic under aggressive driving.


    It's your life and you are welcomed to play Russian roulette with it but when something happens don't say, "I don't know how that happened".

    Is not that I am mean, I just don't sugarcoat what I say.

  • According to the 2015-17 Service manual, the Vehicle Speed Sensor is part of the transmission (picture 7, below), so changing the rear tire will definitely impact speedometer accuracy. The front tires have no impact on speed/speedometer values.

    I have not checked the slingshot, but in the past most of the cars I have checked the speedometer ran off of the transmission so it would seem reasonable if the slingshot did as well

    Cage Free - 2016 Pearl Red SL

    DDM Short Shifter, Sway Bar Mounts Coolant tank Master Cylinder Brace & CAI

    Twist Dynamics Sway Bar, JRI GT Coilovers, Assault Hood Vent

    OEM Double Bubble windshields & various other goodies

  • Interesting I was just repeating what someone else here said that the speedometer reading comes off the front wheels. Guess I can't believe everything I read on this forum. Great info, thx

    don't feel bad, I heard/read the same thing - -

    Cage Free - 2016 Pearl Red SL

    DDM Short Shifter, Sway Bar Mounts Coolant tank Master Cylinder Brace & CAI

    Twist Dynamics Sway Bar, JRI GT Coilovers, Assault Hood Vent

    OEM Double Bubble windshields & various other goodies

  • Interesting I was just repeating what someone else here said that the speedometer reading comes off the front wheels. Guess I can't believe everything I read on this forum. Great info, thx

    I agree as well. Thought it was off the rear, but didn't have personal knowledge, so i didn't question it. I'll melt the rear tire tomorrow and know for sure (but since you already did, we both know the correct answer already)

    Nobody gets outta here ALIVE

  • You might want to print out this article and keep it with you to show the cop who is trying to write you up for speeding. Not all radar detectors are accurate all the time


    https://www.motor1.com/news/43…d-focus-caught-doing-437/

    the breathlizer and the radar both are only as good as the person using them

  • the breathlizer and the radar both are only as good as the person using them

    I was actually pissed off when I got into LE and learned how easy it was to screw someone with radar. You are exactly right, the tools of the trade are only as good as the person using them.


    Tim "Ghost" Ganey
    Winfield, Alabama
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