Correcting for bigger tire size

[bbrown0414]

I have searched for a couple of days and can't seem to fine any info on correcting the pcm for tire size except buy a $300-400 programer. What is the most cost effective way to do this? I am getting ready to go to a 265/70-17 from the stock 16s and want to have everything in order for the switch.

 

[jw1000]

You really don't need to do this. IMO it is not worth the cost of programming it yourself or having someone else do it, because the difference is small and its not so hard to just keep in mind that you're probably going a bit faster than your speedo says.

 

[Elessar65]

The difference you are talking about is about 10%. That's pretty mild, assuming you are going from the 235/70R16 to your 265\70R17. So if your speedo says 65, then you are going 10% faster. 71.5. If it says 45 then you are going 49.5. Not a big deal really, The speedo isn't exactly a precision instrument anyways...

 

[94Eddie]

There are numerous GPS based speedometers you can buy off of ebay or Amazon for around $20. Or you can use a smartphone app to do the same thing.

 

[JungleSkunk]

I went for 235s to 31s and my speedo was off by 7mph. I just got used to it after a while!

 

[jw1000]

There are numerous GPS based speedometers you can buy off of ebay or Amazon for around $20. Or you can use a smartphone app to do the same thing.

Going off of this point, my speedometer is usually not very far off from what Waze says I am going. I jumped from whatever the stock size is to 31 inch tall

 

[domct203]

I was looking to do the same when I lifted and went from a stock tire to a 265/75/16, but I’m just used to the difference now. At 40mph my GPS shows 43MPH, at 65MPH the GPS shows 71MPH.