Speedometer is 5mph off.

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Sep 2, 2004 | 12:48 PM

flat4vw

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Mountain Pass

Joined: Aug 2004

Posts: 162

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From: Roswell, GA

Speedometer is 5mph off.

Hey guys,
The speedomoter on my truck reads 5mph faster than the actual speed. I'm assuming that this is because the previous owner put larger than stock tires on it (but i havent even had time to look at what size they are). Anyways, i was wondering if this means that my odometer is also wrong? My truck is a 1995, 300-6, 5 speed, 2WD and just FYI, it has a digital odometer/trip meter

thanks,
--john

Sep 2, 2004 | 07:11 PM

andym

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Joined: Mar 2002

Posts: 19,402

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From: Bonita Springs FL

Sounds like you have 31" tires on it. That will put it off by about 5mph. And yes, your odometer is off by about 5% too for as long as you had the bigger tires on it.

Sep 2, 2004 | 07:29 PM

flat4vw

Thread Starter

Mountain Pass

Joined: Aug 2004

Posts: 162

Likes: 0

From: Roswell, GA

pretty sure they're not 31's, its a 2WD. I'll check when i get home this weekend. they look smaller than stock, but again, i havent looked up the stock size for that year/bodystyle yet

thanks!

Sep 2, 2004 | 08:19 PM

92lightning

Senior User

Joined: Jul 2002

Posts: 219

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From: SW Michigan

If your tires are smaller than stock ,yes your odemeter would be the same % off as the speedometer. I think that is why the guys with the big tires think they are getting bad milege.

Sep 2, 2004 | 11:15 PM

SoCalDesertRider

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Joined: Dec 2002

Posts: 3,959

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From: USA

Larger than stock size tires cause the speedometer to read s-l-o-w-e-r than actual vehicle speed. Smaller than stock size tires have the opposite effect.

Sep 2, 2004 | 11:15 PM

andym

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Joined: Mar 2002

Posts: 19,402

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From: Bonita Springs FL

The stock size will be printed on the driver's side door post.

Why would anyone put -smaller- tires on a truck?

Sep 3, 2004 | 08:41 AM

flat4vw

Thread Starter

Mountain Pass

Joined: Aug 2004

Posts: 162

Likes: 0

From: Roswell, GA

Quote:

Originally Posted by andym

Why would anyone put -smaller- tires on a truck?

i have no idea - they sure do look pretty though!

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Sep 3, 2004 | 12:01 PM

buddy555

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Joined: Nov 2003

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You can reprogram the speedometer on your truck. There is an article on how to do it in the 'tech articles' section.

By changing tire sizes the speedometer is out by a percentage of the reading on the speedometer, not a fixed value like 5 mph.

Example: When you increase the tire size from 30in to 33in you will be going about 10% faster than the speedometer says you are. At 60 mph on the speedometer you will be going around 66 mph, but at 10 mph on the speedometer you will only be going around 11 mph.