Speedometer accuracy w/31" tires - did dealer lie?
 

Hello,

Got a new '04 Wrangler X in September. I plan to use this jeep for "fun"
driving on-road in warm weather, occasional snow driving (on-road) and
mild off-roading (no serious mudding, rocks or hill-climbing). It is not
a daily driver.

The vehicle is a stock Wrangler X with I6 engine and 3.73 gears. The only
mod is a set of 31" AT tires (Dayton Timberlines, not BFG) and black
wheels with faux beadlock-looking attachments - obviously for appearance
only.

I plan to gradually outfit this jeep with more trail-friendly gear,
although I don't plan to lift it or use larger tires.

My only question at this time is about speedometer accuracy. When I took
delivery, they made me wait for about 45 minutes while the salesguy said
they were making an adjustment so the speedometer would read accurately
with the (dealer-installed) 31" tires.

I happen to have a GPS, and, according to it, the speedometer reads slow
by between 4 to 6 mph.

Is a GPS a good way of measuring speedometer accuracy? I'm not sure if
the dealer just gave me a run-around, did something wrong, or if my GPS is
just not an accurate device for measuring actual vehicle speed (I use it
for geocaching, and it's been very accurate for that).

Thanks for any advice or comments. I enjoy reading this group.

PLM

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[ ]
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Re: Speedometer accuracy w/31" tires - did dealer lie?
 

GPS is dead accurate
"Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..
> Hello,
>
> Got a new '04 Wrangler X in September. I plan to use this jeep for "fun"
> driving on-road in warm weather, occasional snow driving (on-road) and
> mild off-roading (no serious mudding, rocks or hill-climbing). It is not
> a daily driver.
>
> The vehicle is a stock Wrangler X with I6 engine and 3.73 gears. The only
> mod is a set of 31" AT tires (Dayton Timberlines, not BFG) and black
> wheels with faux beadlock-looking attachments - obviously for appearance
> only.
>
> I plan to gradually outfit this jeep with more trail-friendly gear,
> although I don't plan to lift it or use larger tires.
>
> My only question at this time is about speedometer accuracy. When I took
> delivery, they made me wait for about 45 minutes while the salesguy said
> they were making an adjustment so the speedometer would read accurately
> with the (dealer-installed) 31" tires.
>
> I happen to have a GPS, and, according to it, the speedometer reads slow
> by between 4 to 6 mph.
>
> Is a GPS a good way of measuring speedometer accuracy? I'm not sure if
> the dealer just gave me a run-around, did something wrong, or if my GPS is
> just not an accurate device for measuring actual vehicle speed (I use it
> for geocaching, and it's been very accurate for that).
>
> Thanks for any advice or comments. I enjoy reading this group.
>
> PLM
>
> --
> [ ]
> __OIIIIO__
> |||=oo=|||
> ||| |||

Re: Speedometer accuracy w/31" tires - did dealer lie?
 

GPS is dead accurate
"Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..
> Hello,
>
> Got a new '04 Wrangler X in September. I plan to use this jeep for "fun"
> driving on-road in warm weather, occasional snow driving (on-road) and
> mild off-roading (no serious mudding, rocks or hill-climbing). It is not
> a daily driver.
>
> The vehicle is a stock Wrangler X with I6 engine and 3.73 gears. The only
> mod is a set of 31" AT tires (Dayton Timberlines, not BFG) and black
> wheels with faux beadlock-looking attachments - obviously for appearance
> only.
>
> I plan to gradually outfit this jeep with more trail-friendly gear,
> although I don't plan to lift it or use larger tires.
>
> My only question at this time is about speedometer accuracy. When I took
> delivery, they made me wait for about 45 minutes while the salesguy said
> they were making an adjustment so the speedometer would read accurately
> with the (dealer-installed) 31" tires.
>
> I happen to have a GPS, and, according to it, the speedometer reads slow
> by between 4 to 6 mph.
>
> Is a GPS a good way of measuring speedometer accuracy? I'm not sure if
> the dealer just gave me a run-around, did something wrong, or if my GPS is
> just not an accurate device for measuring actual vehicle speed (I use it
> for geocaching, and it's been very accurate for that).
>
> Thanks for any advice or comments. I enjoy reading this group.
>
> PLM
>
> --
> [ ]
> __OIIIIO__
> |||=oo=|||
> ||| |||

Re: Speedometer accuracy w/31" tires - did dealer lie?
 

GPS is dead accurate
"Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..
> Hello,
>
> Got a new '04 Wrangler X in September. I plan to use this jeep for "fun"
> driving on-road in warm weather, occasional snow driving (on-road) and
> mild off-roading (no serious mudding, rocks or hill-climbing). It is not
> a daily driver.
>
> The vehicle is a stock Wrangler X with I6 engine and 3.73 gears. The only
> mod is a set of 31" AT tires (Dayton Timberlines, not BFG) and black
> wheels with faux beadlock-looking attachments - obviously for appearance
> only.
>
> I plan to gradually outfit this jeep with more trail-friendly gear,
> although I don't plan to lift it or use larger tires.
>
> My only question at this time is about speedometer accuracy. When I took
> delivery, they made me wait for about 45 minutes while the salesguy said
> they were making an adjustment so the speedometer would read accurately
> with the (dealer-installed) 31" tires.
>
> I happen to have a GPS, and, according to it, the speedometer reads slow
> by between 4 to 6 mph.
>
> Is a GPS a good way of measuring speedometer accuracy? I'm not sure if
> the dealer just gave me a run-around, did something wrong, or if my GPS is
> just not an accurate device for measuring actual vehicle speed (I use it
> for geocaching, and it's been very accurate for that).
>
> Thanks for any advice or comments. I enjoy reading this group.
>
> PLM
>
> --
> [ ]
> __OIIIIO__
> |||=oo=|||
> ||| |||

Re: Speedometer accuracy w/31" tires - did dealer lie?
 

On Thu, 23 Oct 2003 06:57:06 -0400, Mike T wrote:

> GPS is dead accurate
> "Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
> news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..

>>
>> I happen to have a GPS, and, according to it, the speedometer reads slow
>> by between 4 to 6 mph.
>>

That's what I figured. Any comments from the group on a brand new
Wrangler speedometer reading off by 4-6 mph? Is this to be expected after
"adjustment" at the dealer's to compensate for different tire sizes? (I
expect not, but I'd like others' comments to use at the dealers' to
prevent them just saying "that's a normal amount of error" when it's
probably not.) Has anyone else measured the accuracy of their setup after
adjusting for larger tires?

PLM

--
[ ]
__OIIIIO__
|||=oo=|||
||| |||

Re: Speedometer accuracy w/31" tires - did dealer lie?
 

On Thu, 23 Oct 2003 06:57:06 -0400, Mike T wrote:

> GPS is dead accurate
> "Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
> news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..

>>
>> I happen to have a GPS, and, according to it, the speedometer reads slow
>> by between 4 to 6 mph.
>>

That's what I figured. Any comments from the group on a brand new
Wrangler speedometer reading off by 4-6 mph? Is this to be expected after
"adjustment" at the dealer's to compensate for different tire sizes? (I
expect not, but I'd like others' comments to use at the dealers' to
prevent them just saying "that's a normal amount of error" when it's
probably not.) Has anyone else measured the accuracy of their setup after
adjusting for larger tires?

PLM

--
[ ]
__OIIIIO__
|||=oo=|||
||| |||

Re: Speedometer accuracy w/31" tires - did dealer lie?
 

On Thu, 23 Oct 2003 06:57:06 -0400, Mike T wrote:

> GPS is dead accurate
> "Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
> news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..

>>
>> I happen to have a GPS, and, according to it, the speedometer reads slow
>> by between 4 to 6 mph.
>>

That's what I figured. Any comments from the group on a brand new
Wrangler speedometer reading off by 4-6 mph? Is this to be expected after
"adjustment" at the dealer's to compensate for different tire sizes? (I
expect not, but I'd like others' comments to use at the dealers' to
prevent them just saying "that's a normal amount of error" when it's
probably not.) Has anyone else measured the accuracy of their setup after
adjusting for larger tires?

PLM

--
[ ]
__OIIIIO__
|||=oo=|||
||| |||

Re: Speedometer accuracy w/31" tires - did dealer lie?
 

"Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
news:pan.2003.10.23.13.35.43.926077@ix.netcom.com. ..
> On Thu, 23 Oct 2003 06:57:06 -0400, Mike T wrote:
>
> > GPS is dead accurate
> > "Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
> > news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..
>
> >>
> >> I happen to have a GPS, and, according to it, the speedometer reads
slow
> >> by between 4 to 6 mph.
> >>
>
> That's what I figured. Any comments from the group on a brand new
> Wrangler speedometer reading off by 4-6 mph? Is this to be expected after
> "adjustment" at the dealer's to compensate for different tire sizes? (I
> expect not, but I'd like others' comments to use at the dealers' to
> prevent them just saying "that's a normal amount of error" when it's
> probably not.) Has anyone else measured the accuracy of their setup after
> adjusting for larger tires?

It is completely normal for a speedo to read *high* by a few MPH, not low.
The manufacturers would prefer to err on the safe side. Sounds like they di
not do anything and the larger diameter tires would explain the low reading.

-Fred W


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Re: Speedometer accuracy w/31" tires - did dealer lie?
 

"Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
news:pan.2003.10.23.13.35.43.926077@ix.netcom.com. ..
> On Thu, 23 Oct 2003 06:57:06 -0400, Mike T wrote:
>
> > GPS is dead accurate
> > "Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
> > news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..
>
> >>
> >> I happen to have a GPS, and, according to it, the speedometer reads
slow
> >> by between 4 to 6 mph.
> >>
>
> That's what I figured. Any comments from the group on a brand new
> Wrangler speedometer reading off by 4-6 mph? Is this to be expected after
> "adjustment" at the dealer's to compensate for different tire sizes? (I
> expect not, but I'd like others' comments to use at the dealers' to
> prevent them just saying "that's a normal amount of error" when it's
> probably not.) Has anyone else measured the accuracy of their setup after
> adjusting for larger tires?

It is completely normal for a speedo to read *high* by a few MPH, not low.
The manufacturers would prefer to err on the safe side. Sounds like they di
not do anything and the larger diameter tires would explain the low reading.

-Fred W


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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Re: Speedometer accuracy w/31" tires - did dealer lie?
 

"Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
news:pan.2003.10.23.13.35.43.926077@ix.netcom.com. ..
> On Thu, 23 Oct 2003 06:57:06 -0400, Mike T wrote:
>
> > GPS is dead accurate
> > "Patrick Mills" <plm1954R_E_M_O_V_E@ix.netcom.com> wrote in message
> > news:pan.2003.10.23.10.29.52.293468@ix.netcom.com. ..
>
> >>
> >> I happen to have a GPS, and, according to it, the speedometer reads
slow
> >> by between 4 to 6 mph.
> >>
>
> That's what I figured. Any comments from the group on a brand new
> Wrangler speedometer reading off by 4-6 mph? Is this to be expected after
> "adjustment" at the dealer's to compensate for different tire sizes? (I
> expect not, but I'd like others' comments to use at the dealers' to
> prevent them just saying "that's a normal amount of error" when it's
> probably not.) Has anyone else measured the accuracy of their setup after
> adjusting for larger tires?

It is completely normal for a speedo to read *high* by a few MPH, not low.
The manufacturers would prefer to err on the safe side. Sounds like they di
not do anything and the larger diameter tires would explain the low reading.

-Fred W


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.525 / Virus Database: 322 - Release Date: 10/12/2003