So I have new tire on my hew 2017 wrangler sport and I got the dealer to recalibrate the speedometer and everything for me using flashcal. My question is the flashcal lets you calibrate tire size 32.5 - 32.75 and my tires are 32.6. Should the computer not be programmed for 32.75? At 40mph and above the speedometer is off.
just use your flashcal and set it to 32.50psi or 32.25psi settings and test. Don't use stupid street-alert detectors for speed measurement , use google maps or some other phone accelerometer app like TorquePro to determine your true speed. Ya have to play with the settings a bit on your superchips tuner to get it right ...air pressure in tire can make a difference , environment can , tarmac temp can...you'll find sweet spot but I wouldn't let dealer play with my tuner , heh.
I know it's off at 65 for sure. I think by 2 or 3 mph.
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No I didn't measure them I went off manufacturers specs for the tires.
As far as speed I also used a speedometer app on my phone that registered the same difference as the highway signs. The only reason I mentioned them is I drove 1500 miles and passed 8 of them that all read the same numbers. They were all at least 100 miles or more apart.
You have to measure the tires. Then put that measurement in the procal. When I had my 33's, i put 33 in the procal and my speedo was off ( I didn't know any better at the time). Once i properly measured my tires, and put that number in the procal, the speedo was correct.