Maybe someone can help me i have a 2000 4.0 S type drives great but as soon as it gets to hwy speeds over 60 tractioncontrol light starts flashing and it does not let it resume speed and brings it down when it goes under 60 it comes off and drives fine ? how can i fix this ? also i just recently put 20'' rims on it ..

 

Did it do that before you put the rims on?

What size tires?

 

It was after i put the rims like a day or two later there 20''s .. last night i went ahead and took traction off and it drove fine so im guessing i need to calibrate the ecu? ..

 

You can't. What size tires are you running?

Take care,

George

 

255-30-r20 rear 245-30-r20 front

 

That's your problem....

Mismatched tire sizes. The tires are different diameters. The faster you go the faster the tires spin, eventually the difference in diameter makes the computer think that one set of wheels is spinning and you aren't getting enough traction, so Traction control sets in. 60mph is probably about where you cross the threshold of acceptable variance.

Get 245's all around and you'll be fine.

Take care,

George

 

Will look into it thank you.

 

The tires are all the same height 255 is the width 30 height R 20 so how do they roll faster then the other ?

 

rear tire is just wider then the front

 

30 means 30% of the width. Use a tire calculator.

 

Tire sizes are as follows:

245 <- Tread width in MM / 30 <- Aspect Ratio - as stated Percentage of width that is the sidewall height / R 20 - rim diameter

So your front tires sidewalls are 245x.3 = 73.5 mm x 2 = 147mm

147mm / 25.4 = 5.787 inches + 20 inch rim diameter = 25.787 outer diameter

Rears are:

255x.3 = 76.5mm x 2 = 153mm

153mm / 25.4 = 6.02 inches + 20 inch rim = 26.02 inches outer diameter

Now, 1 mile = 5280 feet. x 12 = 63360 inches

To travel 1 mile your front tires have to rotate 63360/25.87 = 2449 times

To travel the same mile your rear tires have to rotate 63360/26.02 = 2435 times

So if your car is traveling 60mph = 1 mile a min. in 60 seconds, your front tires are turning 2449 times, while your rears are only turning 2435 times. Seems like a somewhat small difference of 14 times less per minute. But you multiply that by 26.02 inches, and it calcuates to 30 feet less per min that the car (which is configured for equal diameter wheels) thinks the rear wheels are traveling. At that point the car thinks the front wheels are slipping, and activates the traction control. Below that speed, the threshold built into the ABS/DSC Ecu doesn't activate.

Hope this makes sense.

Take care,

George