Slick Sizes and Speedometer

USMUCL · 05-18-2025, 03:31 AM

Morning,

I use my HUD speeds on track to improve, particularly with min speed through corners. So, having it accurate is important to me.

Right now, I have 680/305/18 on the front and 680/325/18 on the rear, and the tune is adjusted for it.

Can anyone confirm it's the REAR tires that affect the speedo and not the front? I am likely going to 660 on the front (keeping 680 on the rear), but need to know if that will necessitate a tune change for the speedometer.

Msquared · 05-19-2025, 06:11 AM

IT's the rear tires that determine the speedo reading. It reads the Vehicle Speed Sensor in the tailshaft of the transmission.

USMUCL · 05-19-2025, 06:58 AM

Quote:

Originally Posted by Msquared

IT's the rear tires that determine the speedo reading. It reads the Vehicle Speed Sensor in the tailshaft of the transmission.

Fantastic, thank you.

05-18-2025, 03:31 AM	#1
USMUCL Drives: 2021 Camaro 1SS 1LE Join Date: Aug 2014 Location: Virginia Posts: 406	Slick Sizes and Speedometer Morning, I use my HUD speeds on track to improve, particularly with min speed through corners. So, having it accurate is important to me. Right now, I have 680/305/18 on the front and 680/325/18 on the rear, and the tune is adjusted for it. Can anyone confirm it's the REAR tires that affect the speedo and not the front? I am likely going to 660 on the front (keeping 680 on the rear), but need to know if that will necessitate a tune change for the speedometer.

05-19-2025, 06:11 AM	#2
Msquared Drives: Chevrolet SS 1LE Join Date: Oct 2019 Location: St. Charles, MO Posts: 1,722	IT's the rear tires that determine the speedo reading. It reads the Vehicle Speed Sensor in the tailshaft of the transmission. __________________ Matt Miller 2020 SS 1LE

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