Tire Rotation on 4motion, including spare

[Chris Ratay]

What's the correct pattern for rotating tires on a 4motion?

I've read that 4 motion is different from AWD, and shouldn't be crossed. Tried searching Google with no clear answers, so figured I'd ask here.

I also want to rotate my spare into the mix, so it doesn't end up "too tall" in the future.

* I'm running BFG K02s, non-directional AT tires and traveling in South America.

If I don't rotate and need to use my brand new spare, the tread height could easily be 1.25cm diff, or 2.5 overall - I'm concerned this 1' rolling rate diff could cause drivetrain issues, and I'd like to avoid those, especially traveling so far from home.

 

[WelshGas]

What's the correct pattern for rotating tires on a 4motion?

I've read that 4 motion is different from AWD, and shouldn't be crossed. Tried searching Google with no clear answers, so figured I'd ask here.

I also want to rotate my spare into the mix, so it doesn't end up "too tall" in the future.

I'm running BFG K02s

View attachment 117284

View attachment 117285

Over 9 years I’ve never rotated tyres on my 4 Motion as tyre wear has been equal Front to Rear and NS to Off side. Tyres are changed when tread depth is measured at 3 mm +, normally between 23-25,000 miles. Michelin Cross Climate. These tyres are Directional so I have a Goodyear All Seasons tyre , which is non- directional as an emergency spare.

 

[Velma's Dad]

Most tyres these days seem to be directional, ie they are designed to be used on one side of the vehicle. So swapping tyres laterally is rarely an option, and shouldn't really be necessary anyway.

Like WG I happen to have a non-directional spare. However I'd not be too bothered about having a directional as a spare. In practice the 'directionality' only makes any detectable difference in the very wet**. If I need to fit the spare it's only going to be temporary and I can drive with caution, accordingly.

** I read somewhere at least one on-track test of running directionals 'backwards' and the conclusion was that it made little or no appreciable difference.

 

[Chris Ratay]

I just edited the original post.... I'm traveling in South America on non-directional AT tires - if I need to use my brand new spare, the tread height could easily be 1.25cm diff, or 2.5 overall - I'm concerned this 1' rolling rate diff could cause drivetrain issues, and if like to avoid those, especially traveling so far from home.

Photo from 2 days ago after driving the Trampoline de la Muerta in southern Colombia - I had lowered the pressure to 1.8 bar and needed to top up for the pavement.

 

[Velma's Dad]

I'm traveling in South America on non-directional AT tires - if I need to use my brand new spare, the tread height could easily be 1.25cm diff, or 2.5 overall - I'm concerned this 1' rolling rate diff could cause drivetrain issues, and if like to avoid those, especially traveling so far from home.

I'm no drivetrain expert but I can see no issues. Each axle has a differential - that's of course what allows the wheels to rotate at different speeds, which they do every time you corner. Transmission wind-up should only be an issue if you kept the diffs locked.

Unless anyone knows different about the VW 4-Mo transmission.

 

[WelshGas]

I'm traveling in South America on non-directional AT tires - if I need to use my brand new spare, the tread height could easily be 1.25cm diff, or 2.5 overall - I'm concerned this 1' rolling rate diff could cause drivetrain issues, and if like to avoid those, especially traveling so far from home.

I've been advised that normal tread variation between legally worn and new standard Transporter tyres is within specification for the 4Motion. Obviously if non-standard Transporter tyres are fitted this may not be the case.
With a 2.5 cm difference in tyre diameter between worn and new I presume you have non-standard tyres fitted.
My variation would be a maximum of about 1.2 cm.

 

[WelshGas]

I'm no drivetrain expert but I can see no issues. Each axle has a differential - that's of course what allows the wheels to rotate at different speeds, which they do every time you corner. Transmission wind-up should only be an issue if you kept the diffs locked.

Unless anyone knows different about the VW 4-Mo transmission.

In normal mechanical AWD systems you are correct but the 4Motion is electronically controlled using data from the ABS sensors to control power levels between front and rear axles. Inconsistent ABS data due to different wheel/tyre diameters can cause damage to the Haldex system of regulating and directing drive power.

 

[Velma's Dad]

In normal mechanical AWD systems you are correct but the 4Motion is electronically controlled using data from the ABS sensors to control power levels between front and rear axles. Inconsistent ABS data due to different wheel/tyre diameters can cause damage to the Haldex system of regulating and directing drive power.

Okay understood. But if it can't cope with the difference between a new tyre and a part-worn one on the same axle, it would be pretty stupid. My guess is that it will be no problem in real life.

A brand new AT tyre might have a tread depth of around 12mm (versus 8-9mm for a road tyre). But in practice it seems to me very unlikely someone would still be running a 'fully worn' AT tyre (eg down to say 3mm) as by that stage it would be pretty useless off road. So the difference new vs worn still won't be all that much.

 

[WelshGas]

Okay understood. But if it can't cope with the difference between a new tyre and a part-worn one on the same axle, it would be pretty stupid. My guess is that it will be no problem in real life.

A brand new AT tyre might have a tread depth of around 12mm (versus 8-9mm for a road tyre). But in practice it seems to me very unlikely someone would still be running a 'fully worn' AT tyre (eg down to say 3mm) as by that stage it would be pretty useless off road. So the difference new vs worn still won't be all that much.

True. But you know as well as I do that AT tyres aren't always fitted for function, not in the OPs case, and it does warn about mismatched tyres on a 4Motion in the Handbook, at least it does in mine.

 

[sidepod]

Last week I stood and watched a guy in an Ocean desperately trying to extract it from a wet grassy field with a barely perceptible slope.
He had a lovely big set of bling tyre brackets fitted with huge AT tyres. Neither of us were impressed!
I had to go a fetch my neighbour with his ancient Mitsub 4x4.

 

[Tarquers]

Don’t worry about swapping in the spare. If you destroy a tyre (tire for you ) you will will buy a new tyre with new tread, so you end up in same situation you are trying to avoid…..so…

Keep the spare new, if needed you can then get a new tyre so you have two new tyres on same axle and the old one goes under as a spare, part worn.

This satisfies the mental what ifs you are going through and prevents the hassle of getting under the rear to get the spare out.

Now do I remember a conversation about putting the spare on the rear carrier…

 

[Blue Yonder]

I have directional tyres so just move front wheels to back wheels only. This ensures the tyre wear/ tread depth is reasonably balance across all four corners all the time

Moving wheel side to side is too expensive (not cost effective)as tyres have to be remounted on the wheel due to them being directional

 

[B J G]

I'd expect more of an issue with the tyre pressure monitoring system seeing one wheel rotating at a different rate to the others.
AT tyres start life with a much greater tread depth than 'normal' tyres. can be up to 16mm whereas my CrossClimate SUV's came with 6mm giving much less variation between new and part worn than AT tyres.
I haven't gone to length of checking new & worn circumference measurements on the two types.