Discrepancy between cruise control and speedometer (stock wheels/tires)? (1 Viewer)

[2014 LEX 570 GA]

I am on stock wheels and tires.

Have always noticed a 2-3 mph difference between what my cruise control is set at, the speedometer, and GPS.

The speedometer and GPS are always showing 2-3 mph slower than what the cruise control is set at.

Is this typical?

 

[Madtiger]

My speedo and cruise are same. GPS shows 2 mph slower than what is shown on my dash. I have 2019 LC Stock.

 

[manofthewoods]

My speedo and cruise are same. GPS shows 2 mph slower than what is shown on my dash. I have 2019 LC Stock.

Same vehicle/year, haven't noted any difference, but, haven't really checked either. I will in the next day or so. I'll report if I discover a variance.

 

[bloc]

If you do a long comparison to mile markers on an interstate, you’ll find that on stock tires your odometer is remarkably accurate but the speedo reads fast. This is very common for Japanese cars, and many of mother markets really. They tend to indicate going faster than reality as a margin of error against it indicating slower than you are actually going.. which could lead to liability on their part in the event of an accident.

 

[grinchy]

285/50r20 (stock) actual speed was slower than speedo
275/65r18 actual speed was exactly speedo
275/80r18 actual speed was 10% higher than speedo
35x10.5r17 actual speed is 9% higher than speedo (I use 10% to approximate when it matters.)
For the 35" sizes it actually works out pretty good to just drive the speedo speed on the road sign (60 speedo is 65 real speed, the safe 5 over)

2009 LX570 doesn't have a cruise speed display, but I would bet that display is driven off the abs sensors, same as the rest of the combination meter displays.

 

[coleAK]

My ‘we LX on 31” In the winter and 33”
In the summer. Both wheel sets the cruse is 2-3 mph faster then the Speedo. It has been that way since I got it new

 

[manofthewoods]

My speedo and cruise are same. GPS shows 2 mph slower than what is shown on my dash. I have 2019 LC Stock.

Just checked mine. Set at 60mph, Speedo and cruise (digital) are the same. I used a Garmin GPS (Oregon) and my "smartphone" (Android) to verify. Garmin was ~.5 to 1 mph slower, smartphone was always 1 mph or more slower. Stock Dunlop tires with ~28k miles on them.

 

[2014 LEX 570 GA]

Interesting dispersion.

Well, now that just put 33s on mine, who knows where my speedo relative to cruise and GPS ends up!

 

[Madtiger]

Just checked mine. Set at 60mph, Speedo and cruise (digital) are the same. I used a Garmin GPS (Oregon) and my "smartphone" (Android) to verify. Garmin was ~.5 to 1 mph slower, smartphone was always 1 mph or more slower. Stock Dunlop tires with ~28k miles on them.

For me, i use speed check radars (two of them!) on my route to know that i am consistently 2 mph slower than dash.