I know my speedometer is off now that i got on my 33's. I've read some other members saying its off 10 mph. When i go 15 mph on the speedometer it feels like 15, but im sure its higher. its just that it doesnt feel any faster than 20 mph. Is 10 mph a rough estimate or am i really going 25.

 

its a percentage, not a set speed that youre going to be over at all speeds...

i went from 27's to 30's which is 10% difference, but i checked my speeds via GPS and there was less than 1mph difference at speeds up until 60 when it was about 4-5mph off...

 

Thats what mine was going from 29s to 32s, at 55 I'm doing 60 and at 63 im doing 70ish.

 

oh... i understand now. thanks for the help guys

 

Check w/ford. I have an 03 and they could calibrate it up to 285's for $20.00.

 

You can buy a tuner (pricey option) they can fix your problem, and give you some hp too.

 

not even worth it imo to get it recalibrated... just be conscious of youre speed and if you see a cop just put your needle on the speed limit and youll be fine