In order for this to make sense, TAD's car must have a stability control feature, or whatever it's called that senses a loss of control and cuts engine power and applies individual brakes to bring the car in line with the steering wheel direction. The ECU thinks the front tires, which are smaller and spinning faster than the rear tires, are loosing traction. I thought it was caused by side-to-side differences but apparently it also includes front-to-back differences? The car must have come with the same size tires all around and the previous owner replaced them with different sizes.

I'd like to know for sure whether TAD checked for side-to-side differences. I wish he'd checked tread depth, air pressure, and rolling distance. I guess he'll do whatever he wants to do.

The first question is, can the stability control feature be disabled by a dash switch? If yes, then he could disable it and test the cruise control above 55 mph to check if it remains enabled.

The second question is, can the ECU be reprogrammed to use TAD's current tire sizes? The speedo calculation should be programmable by tire size, but what about stability control? Can front and rear tires sizes be programmed independently?

 

thanks guys.... I will change the tires to four new ones then tell you what happens

 

Well, wait a minute. Did you do the checks? Did you disable whatever you can that detects wheelspin, like ESP, ASR, or whatever and then try the cruise control? I wish you'd do these things before buying new tires.