Can I turn OFF the haldex 4x4 ?

[SB1962]

You can get an upgrade for Haldex with a controller to select more full on modes but I don't think 'off' is an option but it does have an Eco mode which may be nearer to 'Off' than standard.. Not sure if it fits the Scout.

http://www.highperformanceaudi.com/haldex-performance-controller-for-audi

[Howardian1]

Tyres - I got about 25k out of the original Dunlops (from 9k when I bought the car), which is a bit of a shock when my Subaru Forester did about 40k on Bridgestones.

So I run Nokians now (from MyTyres). Summer tyres are Z G2s, winters are WR G2s.

The key question to ask (for durability) is what the treadwear rating of the tyre is. A reference tyre has a rating of 100 - Dunlop SP01s are rated 260. The Nokian Z G2s are 300, whilst the WRGs are a whopping 400.

Clearly there's a relationship between treadwear and price, so the key is to find a reasonably-priced tyre with a high treadwear rating. But then again you may not like the feel of that tyre, or some other characteristic, so it is a bit of a lottery.

[Howardian1]

Just to wrap up the debate about removing the fuse for the Haldex.

Was in the Fuses section of the handbook today looking at something else and happened to notice what is on the same fuse as the Haldex.

"Instrument cluster, control unit for auto gearbox, control unit for power steering; Haldex clutch"

So invalidating the insurance by removing the fuse is even more likely to result in an accident - you won't be able to steer properly and you won't know how fast you were going when you came off the road!

Sorry, but given that every 4WD system (Haldex, permanent Subaru-type, old switchable-type) has some disadvantages somewhere, isn't this an issue that you resolve in your own mind before you buy a 4WD?

[Wardy]

The key question to ask (for durability) is what the treadwear rating of the tyre is. A reference tyre has a rating of 100 - Dunlop SP01s are rated 260. The Nokian Z G2s are 300, whilst the WRGs are a whopping 400.

The treadwear rating isn't all that helpful, as you can't guarantee the figure is directly comparable across tyre manufacturers. They don't use a unified 'open' system (surprise, surprise).

There are also a number of other factors to take into consideration. One large issue would be operational temperature and also driving style. For example, if you ran the winter Nokians at 12 degC over the same route as the summer variant, you would see more aggressive wear on the winters, despite the higher treadwear rating.

[Howardian1]

The treadwear rating isn't all that helpful, as you can't guarantee the figure is directly comparable across tyre manufacturers. They don't use a unified 'open' system (surprise, surprise).

There are also a number of other factors to take into consideration. One large issue would be operational temperature and also driving style. For example, if you ran the winter Nokians at 12 degC over the same route as the summer variant, you would see more aggressive wear on the winters, despite the higher treadwear rating.

Yes, in my post I'd mixed values for summer and winter tyres, which wouldn't be a valid comparison. And it doesn't surprise me that not all manufacturers use the same system. But as a generalisation, I'd hope that a summer tyre with a higher treadwear rating would last longer than a summer tyre with a lower rating, and the same for winters.

Because I have some data I thought I'd test the theory. I (geekishly) record the date, mileage, amount and MPG each time I refuel. Also the dates, mileage and treadwear depth when I swap summer/winter tyres.

So:

All these are for 225/50/R17.

# OE Dunlop SP01 (Treadwear Rating 260). Assuming from 8mm down to binning at 2mm. 23,966 miles (all but 9,322 on my driving).

# Nokian WRG2 (winters) (Treadwear Rating 400). 11,370 miles so far for the loss of 1.5mm = 7,580 miles per mm. Therefore predicted 30,320 miles life if I run them to the recommended 4mm, or 45,480 miles if I run them to 2mm.

# Nokian Z G2 (summers) (Treadwear Rating 300). 12,154 miles so far for the loss of 3mm = 4,051 miles per mm. Predicted life of 24,306 miles, to binning at 2mm.

From that my conclusions are:

# That Treadwear Rating IS a valid factor to consider in longevity.

# For the summer tyres, I'm disappointed that the Nokians don't appear to offer a much longer life than the Dunlops, despite their slightly higher Treadwear Rating.

# The Nokians were however cheaper than the Dunlops would have been (about £35 per corner at the time IIRC), so when you factor price into the equation they are better value for money.

# In future I WILL still ask about the Treadwear Rating of the tyres I'm looking at, so that I can balance price and longevity.

# If the Nokian WRG2s are going to last potentially at least another 4 winters (I do about 5,000 miles each year on winters) then I definitely must get some other rims. Swapping summers to winters will cost me £400 in fitting and balancing charges over that time... And I don't get another set of alloys to show for it!

These ramblings have actually been quite helpful in showing me whether my tyre strategy is working or not, so I hope they're of interest/help to someone else!!

Edited 14 April, 2012 by Howardian1

[Wardy]

Those are all good points, and a nice way of working out and projecting tyre wear too

My main point revolves around the treadwear rating system not being directly comparable across different manufacturers. So having two tyres from two manufacturers, with the same wear rating figure. Problem is they could well still wear at different rates, even given exactly the same conditions (hard to manage in real life I know).

[Howardian1]

Yes, didn't think of it at the time, but my stats would seem to bear that out.

Little difference between the Dunlops at 260 and Nokian Zs at 300.