R50/53 How accurate is the Speedo?

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Apr 3, 2006 | 10:23 AM

#26

Outbackbob

2nd Gear

Joined: Sep 2005

Posts: 143

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From: Medford, Or

There are several roadside radar speed signs in our town around the schools.
I have checked my speed limit at them and I'm always 2 mph over what they show.
If I'm doing 35 mph the signs read 33 mph.

Apr 3, 2006 | 01:53 PM

#27

Aquasar

6th Gear

Joined: Apr 2004

Posts: 1,426

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From: Sumter SC

I am 2mph off per every road side speed sign I pass. So I take that into account where ever I am motoring...

Art

Apr 3, 2006 | 02:24 PM

#28

Mishka

6th Gear

iTrader: (5)

Joined: Oct 2005

Posts: 2,313

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From: Southeast Missouri

Quote:

Originally Posted by wrecker

I am not blessed with GPS, so I do it the old fashioned way. Get on an interstate with mile markers. Set your cruise at 60 MPH and use a stopwatch to see how long it takes to go 1 mile. 60 MPH = 1 mile per minute.

I have to set my cruise at 63 or 64 MPH to click off 1 mile per minute with my Prada Spec 2, and about 61 MPH with the winter snow tires.

From this calculation, you should be able to figure your difference and apply it to any speed.

Just my 2 cents.

As long as the mile markers are actually a mile apart. I bought a new car and was going to check the speedo a few months ago so I was checking mile markers against the trip odometer. I couldn't find two mile markers that were the same, and some varied by quite a bit.

I used to know the method that police use to time vehicles from the air using marks on the pavement, but I'm not sure I remember it exactly so I won't try to explain it here in case I get it wrong. It is a very accurate method. Guess I need to go ask one of my law enforcement aquaintences.