Speedometer question

[Eric]

We went to a wedding last night that was out in the middle of nowhere. I put the gps in my truck and away we went. That was the first time I'd ever had the gps in my truck. Anyway, I would be running 60 mph going by the speedo and the gps said I was doing 64. I've got 35's on my truck but I didn't think it would throw it off that much. Does 4 mph off sound right with 35's

[03-blue-Powerstroke]

That sounds about right. My truck was off 2 mph with just 285/75R16s.

[Eric]

Originally Posted by 03-blue-Powerstroke

That sounds about right. My truck was off 2 mph with just 285/75R16s.

Really? I knew it would be off a little but I thought 4 mph seemed a little high. Guess I need to start watching my speed a little more

[03-blue-Powerstroke]

In Pa we have all of these message boards that tell you your speed. With the combanation of that and my dads gps I figured I was about 2 mph off.

[ianstew]

mine is 2mph off with 235/85/16's

[cliford]

mine is way off. although remeber the faster you go the more the speedo will be off.

[CoalRollinRoosterCruiser]

Should be about 10% off or thereabouts with 35's

[BadAss01F250]

Originally Posted by cliford

mine is way off. although remeber the faster you go the more the speedo will be off.

+1

With 35's my speedo was pretty accurate until around 40mph, by the time I hit 60 it was off by 5mph

[Eric]

Originally Posted by BadAss01F250

+1

With 35's my speedo was pretty accurate until around 40mph, by the time I hit 60 it was off by 5mph

I didn't think about it being farther off the faster you go. I'll have to keep the gps in there for a few days so I can see how much it's off at what speed so I don't get a ticket

[Jarrod B]

Originally Posted by ianstew

mine is 2mph off with 235/85/16's

thats a stock size and its still off?

im running 265/75/16