M

mbrokof

Active Member
Hi,
I just wanted to put the winter tyres on, but forgot to leave a mark on them last time. Trying to figure out which are more worn ones, can't seem to figure it out at the moment as per the picture.

Anyone any suggestion what to do as I also can't find the little tool to measure the tread. I think it's 1/3 and 2/4, but not sure on it.
WhatsApp Image 2021-10-23 at 17.32.20.jpeg

KR
Matthias
 
Those look even to me. You can use a coin for example to measure the tread depth. If there are better ones, those go to the back.
 
Last edited:
Yes, will try that, otherwise put them on. Thanks.

PS Was half a mill difference, but them on the back.
 
Last edited:
I'll use Nodges words here from an other thread to explain why you never want to have more worn (=smaller diameter) tyres on back axle.

Nodge68 said:
As the rear diff is under geared compared to the front, the rear half of the propshaft is turning a bit faster than the front half of the propshaft.
This rear overrunning the front effectively makes the Freelander feel like its a FWD, and also gives a slight delay in VCU activation when grip is lost.
However as the rear is already over greared, putting smaller tyres on the rear over gears it more, forcing the rear diff to drive the IRD pinion faster than the road speed needs, which causes the VCU to start taking torque, which overloads the rear diff and IRD.
Click to expand...
 
I could be wrong here, but if memory serves all tyres are date stamped with the date of manufacture, so it should be easy to spot the newer ones.
 
Vogueman said:
I could be wrong here, but if memory serves all tyres are date stamped with the date of manufacture, so it should be easy to spot the newer ones.
Click to expand...

That is right but the date stamp says nothing about the diameter or tread depth?
 
Stance said:
I'll use Nodges words here from an other thread to explain why you never want to have more worn (=smaller diameter) tyres on back axle.
Nodge68 said: ↑
As the rear diff is under geared compared to the front, the rear half of the propshaft is turning a bit faster than the front half of the propshaft.
This rear overrunning the front effectively makes the Freelander feel like its a FWD, and also gives a slight delay in VCU activation when grip is lost.
However as the rear is already over greared, putting smaller tyres on the rear over gears it more, forcing the rear diff to drive the IRD pinion faster than the road speed needs, which causes the VCU to start taking torque, which overloads the rear diff and IRD.
Click to expand...
Do you not think Nodge68 was referring to smaller size tyres, not a tyre which has an overall lowering effect of less than 1mm?
 
Dee Tees said:
Do you not think Nodge68 was referring to smaller size tyres, not a tyre which has an overall lowering effect of less than 1mm?
Click to expand...
If there's no detectable difference in tread depth, the the VCU won't be activated, which is all the issue would be.
If there's more than a couple of mm difference, then the VCU begins to lock, which overloads the IRD.
 
Nodge68 said:
If there's no detectable difference in tread depth, the the VCU won't be activated, which is all the issue would be.
If there's more than a couple of mm difference, then the VCU begins to lock, which overloads the IRD.
Click to expand...
These tires pictured in the OP look very similar, almost identical, but let's say for the sake of argument there were 2 good and 2 worn (4mm thread diff), how could putting the better tires on the rear (as advised earlier) be more VCU friendly? Would it not be the same strain for the VCU as having them on the front?
 
Dee Tees said:
These tires pictured in the OP look very similar, almost identical, but let's say for the sake of argument there were 2 good and 2 worn (4mm thread diff), how could putting the better tires on the rear (as advised earlier) be more VCU friendly? Would it not be the same strain for the VCU as having them on the front?
Click to expand...

The rear diff is under geared compared to the front, so with 4 identical tyres, the rear diff turns the rear shaft of the VCU slightly faster than the IRD is turning the front VCU shaft.
If the rear tyres are smaller than the front by more than a couple of mm, then the rear diff spins the rear shaft of the VCU fast enough for the VCU to start transferring considerable torque to the IRD, which causes it to fail.
Having larger rear tyres reduces this rear driving front effect, which continues to reduce as the front tyres wear.
 
Dee Tees said:
These tires pictured in the OP look very similar, almost identical, but let's say for the sake of argument there were 2 good and 2 worn (4mm thread diff), how could putting the better tires on the rear (as advised earlier) be more VCU friendly? Would it not be the same strain for the VCU as having them on the front?
Click to expand...
Because the IRD gearing to the prop shaft PTO combined with rear dif gearing means that the front and rear axles turn at slightly different speeds.

The designers put this slight difference in to make the car feel like a 'modern' front wheel drive. This means that for each turn of the engine, the front wheels turn slightly more so that they are doing most of the pushing along with the rear wheels slightly 'lagging' so as not to feel as though they are pushing the car. This slight difference is allowed to slip by the VCU.

If you put the less worn, larger diameter, tyres on the front, then this magnified this difference in speeds because the front wheels are moving further per turn. This means that the VCU has to allow more slippage and is therefore getting towards the point where it 'locks up' (not actually locking up, but creating more wind up).

Therefore putting the less worn, larger diameter, tyres on the rear may reduce the feel of a front wheel drive car, but is also reducing the slippage that the VCU is having to make.
 
Nodge68 said:
I use a digital caliper. However if you can't tell by looking, then it makes no difference to the vehicle. ;)
Click to expand...
Thanks Nodge68. Also for the good explanation. Never read it in that detail. I always understood rear more than front and 6.5 is more than 6mm. Always good to have a dangerous half knowledge:D.
 
GrumpyGel said:
Because the IRD gearing to the prop shaft PTO combined with rear dif gearing means that the front and rear axles turn at slightly different speeds.

The designers put this slight difference in to make the car feel like a 'modern' front wheel drive. This means that for each turn of the engine, the front wheels turn slightly more so that they are doing most of the pushing along with the rear wheels slightly 'lagging' so as not to feel as though they are pushing the car. This slight difference is allowed to slip by the VCU.

If you put the less worn, larger diameter, tyres on the front, then this magnified this difference in speeds because the front wheels are moving further per turn. This means that the VCU has to allow more slippage and is therefore getting towards the point where it 'locks up' (not actually locking up, but creating more wind up).

Therefore putting the less worn, larger diameter, tyres on the rear may reduce the feel of a front wheel drive car, but is also reducing the slippage that the VCU is having to make.
Click to expand...
Also here, thanks for the good explanation:)
 
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