Cayenne tyres scrubbing on tight turns
Discussion
Hi, had my new Cayenne for 1k miles now and out of tight turns it still really jumps at low speed or crabs I guess you could say. I thought once the tyres wear a bit or warmer days it’ll help but it’s pretty violent some times. Anyone else had this? Or worth sending to dealer for geo check.
Thanks
Thanks
Yes, it's a standard feature. The two front wheels don't turn exactly right for the geometry of the turn you're trying to drive so tension builds up and it's good for it to be released somewhere, typically by one tyre skipping a bit. If you fit grippier tyres to cure the effect you're containing all that tension inside the steering system which may lead to increased wear.
If you don't like the effect, just use a bit less steering lock when you turn.
If you don't like the effect, just use a bit less steering lock when you turn.
Pablo Escobar said:
Ackerman effect
This! Porsche's are an arse for it. You won't notice it as much during the summer when the tyres are warmer and softer. My Cayman was a b
h in cold mornings coming off the drive, used to make me wince as you can feel the inside tyre being dragged across the surface...
Also had RWD Mercedes & BMW and they do not it anything like as much, if at all.
Which year / model of Cayenne? * Edited to add - having read properly - it's a new one in which case ignore the below!
955 had an electric torque varying transfer case which the actuator is the first thing that goes offline when battery voltage is low hence the 4wd fault on the display panel.
957 had the same but a different control module which operated the actuator less thus saving battery power and not burning out the actuator.
958 petrols had a transfer box similar to the above but made of chocolate, diesel's had a simpler torsen style but there is confusion as to which oil to put in it.
Models after this I don't know as I don't own one.
Porsche service intervals are too long on them (and especially the axle differentials) so at the very minimum make sure the oil is changed.
955 had an electric torque varying transfer case which the actuator is the first thing that goes offline when battery voltage is low hence the 4wd fault on the display panel.
957 had the same but a different control module which operated the actuator less thus saving battery power and not burning out the actuator.
958 petrols had a transfer box similar to the above but made of chocolate, diesel's had a simpler torsen style but there is confusion as to which oil to put in it.
Models after this I don't know as I don't own one.
Porsche service intervals are too long on them (and especially the axle differentials) so at the very minimum make sure the oil is changed.
trevalvole said:
I recall that when it was reported to occur on Merc G-somethings, that they recommended fitting all season tyres, which would fit in with the comment above about softer rubber.
Yes the G I had did it but only for first 200 miles. rs6 too even with rear wheel steer. But the Porsche is really bad, even with less lock on. Wilco500 said:
Hi, had my new Cayenne for 1k miles now and out of tight turns it still really jumps at low speed or crabs I guess you could say. I thought once the tyres wear a bit or warmer days it ll help but it s pretty violent some times. Anyone else had this? Or worth sending to dealer for geo check.
Thanks
It's a miss match between the geometry setup and the tyre construction that can show up all the time or more likely in certain conditions like cold weather. Some will refer to the Ackerman effect, almost justifying it because it has a fancy title, but IMHO a family SUV should not be dragging it's tyres each time you reverse into the driveway. It destroys the tyres and gives various suspension arms a hard time. Thanks
I've experienced it to some degree on several Macan's & my GT4 finding it to be very trye depended with Pirelli PZero the worst culprit on the Macan once the temperature drops. I've just removed the 21" wheels with PZeros & fitted 20" wheels & winter tyres (Pirelli Scorpions) and the issue disappeared completely as the tyre has much more 'give' at lower temps. To be frank, the car feels so much better around town on the winter tyres.
Pablo Escobar said:
Ackerman effect
More that it is the lack of Ackerman effect, i.e. the inside wheel isn't turning at the correct angle.It is an intentional compromise on performance cars to reduce understeer. The only cure* is to have less performance-oriented tyres/wheels so that there is more give in the tyre.
For a Cayenne for example, being on 18 inch wheels (taller sidewall) and winter/all-season tyres that aren't at 45 psi would almost certainly fix it.
( *Or, steer-by-wire where each wheel is controlled independently so that the ackerman angle can be changed depending on the type of driving you're doing. No thanks
) I think/suspect it is Porsche developing tyres to maximise their cars performance in certain conditions. If it was purely geometry/mechanical surely the tyres wouldn t have such a big effect. Very familiar with it because we run a Macan and a Cayenne one of which runs winter tyres in season.
Worth remembering that in a lot of Porsche’s biggest markets running winter tyres is obligatory so the performance of summer tyres in the wet/cold will not be of any real concern to Porsche when they specify them. They will be more concerned with handling characteristics on a fast drive on a summer’s day than driving at walking speed in a cold/wet car park in the middle of winter.
Winter tyres have material benefits to braking distances in the wet/cold…not just grip in the snow !
Worth remembering that in a lot of Porsche’s biggest markets running winter tyres is obligatory so the performance of summer tyres in the wet/cold will not be of any real concern to Porsche when they specify them. They will be more concerned with handling characteristics on a fast drive on a summer’s day than driving at walking speed in a cold/wet car park in the middle of winter.
Winter tyres have material benefits to braking distances in the wet/cold…not just grip in the snow !
Edited by Cheib on Thursday 11th December 11:24
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