[rogerxp]

...was the excuse given to me today by a techy at Nissan .

Over the last couple of weeks my Zed has started to emit a rumble/grinding when on full lock at really low speeds i.e. reversing off my driveway or pulling out of my office carpark onto the road.

The sound/sensation soon passes and normal lunatic driving commences.

Was passing Westway Stockport today so nipped in to see if a techy could have a gander and offer some advice. He quickly checked the tread of the fronts and said "the tyres are too wide". I looked a little bemused so he enlightened me further. They are finding that when the tread starts to get on the low side (3mm in my case), because the fronts are so wide (the same width as the rears on a 350Z), they literally lose grip so the rumbling is the tyres just being dragged/pushed as opposed to turning the way they're pointing; kind of understeer. As soon as your increase your speed all grip returns.

Odd.

[zltm089]

huh.....

[rogerxp]

Originally Posted by zltm089

huh.....

How's about this for a reply from the Zed forum...

Is it a low grumble or more like a thump thump thump?

The thumping is kind of what they are describing but its not purely because the tyres are too wide. When you turn the wheels of the car to full lock, the camber of the wheel changes such that it tilts the wheels over to extreme angles and decreases the contact patch on the road. This means the car will scrabble for grip, jumping from having grip, to no grip, to finding it again. Its a nasty sensation and completely normal in the 370z. Its because the car has big front tyres and also because they wanted to keep the turning circle smaller, and in this country with cold weather (less maluable tyres), it scrabbles on full lock. When going faster, the inertia will push the weight to the outside and correct this angle and so contact patch is right again, but slow speeds it doesnt have the weight on the contact patch.

Go outside and stick the car on full lock and look at the tyres, you'll see what I mean

[M3-FAST]

They are corect Roger - the Porsche is doing it on my block paved driveway, and it worried me at the weekend as I was worried it had a problem with a steering joint or similar.

Anyway, a quick google search showed lots of similar questions asked on Porsche forums, and it is totally normal. Apparantly it shows up worse in the cold weather?

Sure enough, was backing the A7 off the drive this morning and as it was on full lock in reverse, I experienced a similar feeling.

It is something to do with the width of the tyres as the inner edge of the tyre is trying to do a tighter turning circle than the outside - maybe when the tyres are warmer and more pliable then you don't notice as much

[rogerxp]

Yup, that's exactly it, don't know whether it's audible from the outside or not but it could be quite embarrassing if it is . My Bridgestones are hard as fook in this cold weather hence why my tail wags like a good un under anything other than very delicate driving .

[Ant Man]

This is called tyre scrub, right? I suppose the very cold weather has an impact too.

[rogerxp]

Originally Posted by Ant Man

This is called tyre scrub, right? I suppose the very cold weather has an impact too.

Yup, I'd say cold defo is 100% to blame, I've owned the car since April and this is the first time it's happened (over the last two week). Now it's constant, on full/near-full lock, at crawling speeds. My tyres are now rock hard, hence the miniscule levels of grip, and 'tyre-scrub'. Roll on summer.

[MEGA]

You're doing it wrong..