Correcting Speedo for new tire size

['14 Shelby]

I tried to search but couldn't find anything on this although I'm sure I've seen it before.

Anyway my original tires were 255/40/19 (I think) from the original Brembo wheels. I'm now on 315/35/20 on the rear. I know my speedo is off (that's what she said) but can't figure out where in the SCT I can make an adjustment for this. I contacted SCT and they said that would be only for preloaded tunes. Under Adjust/Options or something to that effect, but I find nothing.
I had a preloaded tune then dyno. Anyway can this be adjusted?

 

[nosympathy]

I tried to search but couldn't find anything on this although I'm sure I've seen it before.

Anyway my original tires were 255/40/19 (I think) from the original Brembo wheels. I'm now on 315/35/20 on the rear. I know my speedo is off (that's what she said) but can't figure out where in the SCT I can make an adjustment for this. I contacted SCT and they said that would be only for preloaded tunes. Under Adjust/Options or something to that effect, but I find nothing.
I had a preloaded tune then dyno. Anyway can this be adjusted?

Who do you have tunes through? they can turn that menu for your turn off and on. Basically you select your tune, it asks if you want to adjust other parameters, then you can tune the car. It leaves the ability to adjust the revs per mile open.

If you don't have this option, contact your tuner to open this up for you, or make the change in the tune itself for you.

My tunes through bama never had this option open to make changes unless I told them to leave it open. Which they still rarely did anyway. When running AED now, Shaun leaves this open and I can change idle rpm, max rpms in neutral, while driving, rear diff gear ratio, revs per mile, etc.

 

[UnleashedBeast]

You have to adjust "tire rev per mile" in your SCT tuner. Only custom tunes where the tuner left the options unlocked can you adjust this.

www.tirerack.com has a lot of information on tire specifications. You can find out what tire rev per mile is on just about any tire. If that spec isn't listed, you can go to the manufacturers website.

Factory Brembo Goodyear tires rev per mile is 774

 

['14 Shelby]

Great thanks guys

 

[zachcrosen]

Yeah Bama tunes don't allow you to change things due to their warranty.


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[nosympathy]

Yeah Bama tunes don't allow you to change things due to their warranty.


Sent from my iPhone using Tapatalk 2

Maybe, i've talked them into it before. They just don't have great QC and tunes would be all over the place. Sometimes forgetting to turn the rear 02s off throwing cels, etc. onward. I put up with them for a while, but recently after dealing with their inability to tune for the Boss IM on my car, I dumped them quick as I could.

 

[UnleashedBeast]

IMO, all aftermarket tuners should leave tire rev per mile unlocked by request. I always request this.