This might help too..... Don't tell anyone im giving out technical info though as im not renowned for it on this site
Q: The "Slip" light come on randomly, especially in turns, even though my tires aren't slipping. What's up with that?
A: Both the Traction Control System (TCS) and Vehicle Dynamic Control (VDC) can cause the "slip" light to come on. There are a couple of things that can make it come on even though you don't feel/hear your tires slipping.
The most common cause for this behavior is replacement of the OEM tires with a different size. All Zs come with staggered tires, that is to say the fronts are a little shorter than the rears. This causes the tires to rotate at different rates which TCS and VDC depends on for normal operation. If you install tire combinations that don't maintain that stagger, it can cause problems for TCS/VDC resulting in the "slip" light illuminating.
The stock tire sizes and Outside Diameters are:
225/50/17 25.9"
235/50/17 26.3" (0.4" stagger)
225/45/18 25.9"
245/45/18 26.7" (0.8" stagger)
245/40/18 25.7"
265/35/19 26.3" (0.6" stagger)
When choosing new tires, try to find front/rear pairs that maintain the stagger of at least ½" and less than 1". You should also look for front/rear setups that maintain the same OD as that will keep your speedometer and odometer accurate.
Here are the most common "upsized" tire combinations. These are known to work and keep TCS/VDC happy.
245/40/18 25.7"
275/40/18 26.6" (0.9" stagger)
245/35/19 25.8"
275/35/19 26.6" (0.8" stagger)
Check the manufacturer's website to find the Outside Diameter of tires before you buy them, or use one of the online tire calculators:
http://www.miata.net/garage/tirecalc.html
http://www.wheelsmaster.com/rt_specs.jsp
A less common cause for the "slip" light to illuminate comes from replacing the fronts or rears only. If you replace only the fronts or rears, the stagger may not be what you think it is because the other worn pair is actually up to ½" smaller than they were when new.
New tires also come with a release agent on the surface of the rubber that must be worn off. That makes them slick and can result in your tires actually slipping, hence the "slip" light.
NOTE: The slip light does and will come on during "normal" driving that is unrelated to tire size or wear. If you apply too much throttle when launching or going around a turn, the wheels will slip and cause the light to illuminate. Also, driving on slick road surfaces (water, oil, rocks) can also cause your tires to slip.
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