On Fri, November 17, 2006 1:56 pm, jon@dakota-truck.net said:
>
> Assuming that your computer is calibrated for a 31" tire, if
> you are running 32s now, your mileage and speedometer readings are
> going to be reading low by just under 3.3%. So, if your speedometer
> says you are going 50mph, you're actually going 51.6mph.
Note that speedometers aren't necessarily very accurate even with factory
tires. There's an allowable variance under the law, although I don't know the
exact amount.
I've checked both of our trucks against the GPS. Assuming the GPS is correct
(and they usually are), the '95 actually moves slower than the speedometer
says, and the '01 moves faster. It's a difference of about 2 MPH at 60 in
both cases. Both trucks are running factory size tires, although I have NOT
bothered to do any kind of scientific test involving measuring the tire
pressure and remaining tread depth or anything like that (nor do I intend to).
For whatever that's worth.
-- Jason Bleazard http://drazaelb.blogspot.com Burlington, Ontario his: '95 Dakota Sport 4x4, 3.9 V6, 5spd, Reg. Cab, white hers: '01 Dakota Sport 4x4, 4.7 V8, Auto, Quad Cab, black
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