Speedometer help
Fleet Owner
Joined: Apr 2012
Posts: 27,307
Likes: 549
From: Spanaway
You may find this tool useful on the RPM of the tire per mile.
Tire Calculator
With this info you can find the right # to make the correction.
Sean
Tire Calculator
With this info you can find the right # to make the correction.
Sean
Senior User
Joined: Nov 2005
Posts: 269
Likes: 0
From: Saukville WI
PSD2005 3mph off isn't too bad my 91 f-150 has 33's its like 8mph off - dosent bother me
Hotshot
Joined: Aug 2006
Posts: 17,398
Likes: 317
From: Whittier, CA
Yeah, lots of theories about why the do that. Some think it is Ford cheating owners on the warranty period. Maybe. I think they just want the error to be toward the slow side, so they don't get sued every time someone gets a speeding ticket.
I went from stock 31.5" tires to 33" ties, and now my speedo is about 3mph off in the other direction. It's still close enough to not be an issue.
Before the wonderment of GPS, we would have never known such a minor error existed.
I went from stock 31.5" tires to 33" ties, and now my speedo is about 3mph off in the other direction. It's still close enough to not be an issue.
Before the wonderment of GPS, we would have never known such a minor error existed.
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Certified Thread Hijacker
Joined: Aug 2001
Posts: 14,441
Likes: 59
Yeah, lots of theories about why the do that. Some think it is Ford cheating owners on the warranty period. Maybe. I think they just want the error to be toward the slow side, so they don't get sued every time someone gets a speeding ticket.
I went from stock 31.5" tires to 33" ties, and now my speedo is about 3mph off in the other direction. It's still close enough to not be an issue.
Before the wonderment of GPS, we would have never known such a minor error existed.
I went from stock 31.5" tires to 33" ties, and now my speedo is about 3mph off in the other direction. It's still close enough to not be an issue.
Before the wonderment of GPS, we would have never known such a minor error existed.
The only way to throw the speedo off would be to install taller tires, and well the manufacturer is no longer liable.
Josh
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