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Whats The Maximum Difference In Front Rear Tyre Diameter Attesa Can Handle?

fungoolie

By fungoolie,
in R35 GTR

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fungoolie Community Regular

fungoolie

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Does anyone know what Nissan says the car will tolerate in front/rear rolling diameter difference? I mean just having worn tyres on one axle and new ones on the other should create around a 2.5% difference. And what happens if you exceed this threshold? Will the car's warning systems tell you it's not happy?

Edited by fungoolie
LSX-438 Mentor

LSX-438

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Does anyone know what Nissan says the car will tolerate in front/rear rolling diameter difference? I mean just having worn tyres on one axle and new ones on the other should create around a 2.5% difference. And what happens if you exceed this threshold? Will the car's warning systems tell you it's not happy?

If the front/back is out too much (i think the threshold is closer to 4%) then the traction control system will invoke and pull power (thinks you are are wheel spinning basically). Also I found the system cannot deal with tyres less than 640mm in height. It does the same thing, i guess it concludes the wheel speed is too high and pulls power as it think you are out of control. In this case you have to turn VDC off, otherwise everything else works fine.

fungoolie Community Regular

fungoolie

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If the front/back is out too much (i think the threshold is closer to 4%) then the traction control system will invoke and pull power (thinks you are are wheel spinning basically). Also I found the system cannot deal with tyres less than 640mm in height. It does the same thing, i guess it concludes the wheel speed is too high and pulls power as it think you are out of control. In this case you have to turn VDC off, otherwise everything else works fine.

Thanks for that Duncan. So the VDC kicks in well before you start to put the centre diff at risk. I'd love to know how the car knows you have small diameter tyres on it short of using the GPS to determine the true vehicle speed.

LSX-438 Mentor

LSX-438

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Posted (edited)
Thanks for that Duncan. So the VDC kicks in well before you start to put the centre diff at risk. I'd love to know how the car knows you have small diameter tyres on it short of using the GPS to determine the true vehicle speed.

I guess working out front/back difference is easy, but yeah dunno what it does to determine smaller wheels diameter. Some guys reckon it doesnt/can't know, and that what i am seeing is simply wheelspin brought about by gearing. I beg to differ though, i reckon the GTR somehow knows. Perhaps it is comparing wheel speed to something. Perhaps when it goes over a certain threshold, vs gear vs engine speed, it gets confused. R35 has all sorts of crazy stuff, someone told me if you press hard enough on the steering wheel the system thinks you have just had a crash and will go into limp mode. Too smart by half.

Edited by LSX-438

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