Speedometer adjustment

Discussion in 'Chevy Truck Talk & GM News' started by Alarmguy, Sep 23, 2012.

  1. Alarmguy

    Alarmguy New Member

    How can I adjust my speedometer to compensate for tires that are larger than my factory size. Is this a dealer thing or can i do it myself?
     
  2. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I'm unsure how this sort of thing is handled on pre-99 trucks, but on 99 and later models the truck's computer has to be programmed for the overall diameter of the tires. Either go to the dealership and pay them to do it or buy a handheld programmer and use it to do it.

    Be advised that the computer is finicky about certain tires sizes and will turn on the ABS idiot light if it doesn't like a size you've set with a handheld programmer. (My tires are technically 34.3" in diameter, so 34.5" would have been a logical setting and it tossed the ABS light ... but it was perfectly happy with 34" as the setting, so that's what I used.)
     
  3. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner Gold Member 1000 Posts

    either a programmer or superlift used to sell a speedometer calibrator (which is what I have). It is hard wired in and you can switch between 2 sizes with a switch as well as fine tune it if you notice it is still off a little.
     
  4. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    That's another approach. What'd that run, [MENTION=26043]dsfloyd[/MENTION]? I ask because if I were going to sink cash into something I'd want it to do more than just the speedo adjustment ... unless it was super cheap. Programmers run in the multiple hundreds of dollars but do all sorts of things. What'd the speedo calibrator set you back?
     
  5. McClintoc

    McClintoc ɹoʇɐɹǝpoɯ Staff Member 2 Years 1000 Posts Platinum Contributor

    A speedo recalibrator plus OBD II code reader would be a worthwhile investment. I'll probably put over-sized tires on every truck I own so it would be a good thing to have handy.

    As for my truck, it came stock with 245-75-16s and I currently have 265-75-16s it. I have driven past enough of those speed limit signs that show you your speed to know that my truck is actually going 2 mph more than what the speedo says.
     
  6. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    You trust what the government tells you (even by way of machines it owns)??? Shame on you!
     
  7. McClintoc

    McClintoc ɹoʇɐɹǝpoɯ Staff Member 2 Years 1000 Posts Platinum Contributor

    Touche! I shall get my speedo adjusted, post haste! :lol:
     
  8. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner Gold Member 1000 Posts

    Sorry surrealone that it took so long to get back to your question. I think it was about $215(correction from previously posted price). I will see if they even still sell it.
     
    Last edited: Oct 5, 2012
  9. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    No worries, I didn't need the data. It was more for comparative use by those considering a programmer versus a device that just adjusts the speedo...
     
  10. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner Gold Member 1000 Posts

    Ok I just looked around to see the price and it varys from $210-$240 so disregard the earlier price posted, the ABS light correction (for 4.56 and above gears) is what runs around $100.
     

Share This Page

Newest Gallery Photos