Cruise control and tire size--is this the source of the problem?
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Senior Member
Joined: Dec 2001
Posts: 494
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From: Amber waves of grain.
2000 CLK430 Cabriolet
Cruise control and tire size--is this the source of the problem?
Cruise control and tire size--is this the source of the problem?
My cruise control will disengage after a while on the highway.
Never had this problem before. I try to cruise at Approx. 77 MPH.
Here are my tire/wheel sizes.
Front: 225/40R18 Kumho Ecsta ASX, Revs. per mile: 829.3
Mounted April, 2010 at 104,000 miles.
Rear: 255/35R18 Kumho Ecsta ASX, Revs. per mile: 831.3
Mounted Sept. 2010 at 110,911 miles.
Could this be causing my cruise control to deactivate ?
If not, then what is a fix to keep the cruise control from deactivating.
When it deactivates, it will not re-engage, unless I pull off the road, shut down, then restart the car.
Thanks
PS. Used a chart on the net to calculate revolutions per mile. See attachment.
My cruise control will disengage after a while on the highway.
Never had this problem before. I try to cruise at Approx. 77 MPH.
Here are my tire/wheel sizes.
Front: 225/40R18 Kumho Ecsta ASX, Revs. per mile: 829.3
Mounted April, 2010 at 104,000 miles.
Rear: 255/35R18 Kumho Ecsta ASX, Revs. per mile: 831.3
Mounted Sept. 2010 at 110,911 miles.
Could this be causing my cruise control to deactivate ?
If not, then what is a fix to keep the cruise control from deactivating.
When it deactivates, it will not re-engage, unless I pull off the road, shut down, then restart the car.
Thanks
PS. Used a chart on the net to calculate revolutions per mile. See attachment.
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Joined: Apr 2005
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From: SCV SoCal
2002 CLK430
According to Kumho, the revs per mile rating on their Ecsta ASX KU21 in a 225/40-18 is 828, and the 255/35-18 is 831. This is the webpage for the specs on their Ecsta ASX KU21 You were REALLY close! Unfortunately, it's not the tires.
I would guess the problem is one of the wheel speed sensors is flakey. To calculate speed, the instrument cluster looks at all four wheel speed sensors. If one sensor supplies a number that’s far enough off from the other three, the speedo uses the left front sensor and the cruise is disengaged.
Try dumping the codes. HOPEFULLY you get a 'this specific sensor is bad' code.
I would guess the problem is one of the wheel speed sensors is flakey. To calculate speed, the instrument cluster looks at all four wheel speed sensors. If one sensor supplies a number that’s far enough off from the other three, the speedo uses the left front sensor and the cruise is disengaged.
Try dumping the codes. HOPEFULLY you get a 'this specific sensor is bad' code.
Last edited by MarcusF; Dec 31, 2010 at 07:32 PM.
Thread Starter
Senior Member
Joined: Dec 2001
Posts: 494
Likes: 13
From: Amber waves of grain.
2000 CLK430 Cabriolet
Thanks Marcus.
Will clear the codes and see what pops up.
Does it make sense, that, since the system uses the left (driver) front sensor as an index, that, if I don't get any good feedback from the codes, then I should replace the left (driver) front sensor first ?
Also, I seem to recall some sensors Re. brake pad wear. Are these the same sensors as the rpm sensors we are talking about ?
Will clear the codes and see what pops up.
Does it make sense, that, since the system uses the left (driver) front sensor as an index, that, if I don't get any good feedback from the codes, then I should replace the left (driver) front sensor first ?
Also, I seem to recall some sensors Re. brake pad wear. Are these the same sensors as the rpm sensors we are talking about ?
Thread Starter
Senior Member
Joined: Dec 2001
Posts: 494
Likes: 13
From: Amber waves of grain.
2000 CLK430 Cabriolet
