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Is all wheel drive worth the money?

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On 4/16/2018 at 10:51 AM, iRage said:

Only time we got hit by a huge and utter loss was when the duty structure changed. So you have a greater risk of losing money because of the duty structure changes than because the car was AWD.

yhh gud point there :D

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On 4/16/2018 at 7:41 PM, Junkfriend said:

yhh almost imposible :( , sometimes I really miss burning some rubber .... 

Seriously mate? recall Sri lanka? Expensive tyres? Bad roads?;)

What do you drive??

 

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On the topic of AWD

On my Hiace sun visor there is a information/warning which says to use same brand, same model tyres on all four wheels. I guess this to prevent the AWD system getting confused 

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49 minutes ago, Magnum said:

On the topic of AWD

On my Hiace sun visor there is a information/warning which says to use same brand, same model tyres on all four wheels. I guess this to prevent the AWD system getting confused 

Yes...different tyre types and brands will have varying grip levels depending on things like thread cut and depth, rubber hardness etc....so the system can get confussed

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1 hour ago, iRage said:

Yes...different tyre types and brands will have varying grip levels depending on things like thread cut and depth, rubber hardness etc....so the system can get confussed

Also if I remember right the 4WD Hiace requires same tyre pressure front and back while the 2WD model has different tyres pressures.

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Posted (edited)

Apart from what iRage mentioned, it's recommended that you have the same tyre pressure* all round in order to minimise wear on the AWD system. Especially in AWD systems where torque transfer happens through electronically operated hydraulic clutches, having the same tyre all round and maintaining the same pressure is critical for longevity of the system. Failing to do so can lead to premature wear in the system as the wheel with the smaller diameter causes the clutches to slip in order to keep up (because it has to spin more). This can cause the differential to build up excessive heat.

*EDIT: It should be equal rolling diameter and not equal tyre pressure. 

Edited by Davy
Added clarification for inaccurate content

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On 4/19/2018 at 11:21 AM, Davy said:

Apart from what iRage mentioned, it's recommended that you have the same tyre pressure all round in order to minimise wear on the AWD system. Especially in AWD systems where torque transfer happens through electronically operated hydraulic clutches, having the same tyre all round and maintaining the same pressure is critical for longevity of the system. Failing to do so can lead to premature wear in the system as the wheel with the smaller diameter causes the clutches to slip in order to keep up (because it has to spin more). This can cause the differential to build up excessive heat.

 

You are absolutely wrong!

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26 minutes ago, Junkfriend said:

You are absolutely wrong!

Unless you're going to defend that with details, I'm not even going to bother say anything except that I drive a Mitsubishi with an AWC system and the owner's manual specifically warns against running with unequal tyres and different tyre pressures.

Don't take my word for it, do a Google search. 

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1 minute ago, Davy said:

Unless you're going to defend that with details, I'm not even going to bother say anything except that I drive a Mitsubishi with an AWC system and the owner's manual specifically warns against running with unequal tyres and different tyre pressures.

Don't take my word for it, do a Google search. 

In that case brother you should have said "I recommended that you have the same tyre pressure all round" in Mitsubishi vehicles because in all brands you don't need to do that, especially ones with AWD with dynamic systems, actually they even give you warnings if you if you put 5 passengers with with same PSI on all wheels.    

And no I don't need to google as its says so in owners manuals :)  

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2 hours ago, Davy said:

Unless you're going to defend that with details, I'm not even going to bother say anything except that I drive a Mitsubishi with an AWC system and the owner's manual specifically warns against running with unequal tyres and different tyre pressures.

Don't take my word for it, do a Google search. 

This is common in My AWD Vitara as well. It has to be the same psi on all 4 corners.

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7 hours ago, Junkfriend said:

In that case brother you should have said "I recommended that you have the same tyre pressure all round" in Mitsubishi vehicles because in all brands you don't need to do that, especially ones with AWD with dynamic systems, actually they even give you warnings if you if you put 5 passengers with with same PSI on all wheels.    

And no I don't need to google as its says so in owners manuals :)  

I would simply follow the info on the tire info tag on the driver side door..

IMG_0911 (2).jpg

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Posted (edited)
9 hours ago, Junkfriend said:

In that case brother you should have said "I recommended that you have the same tyre pressure all round" in Mitsubishi vehicles because in all brands you don't need to do that, especially ones with AWD with dynamic systems, actually they even give you warnings if you if you put 5 passengers with with same PSI on all wheels.    

And no I don't need to google as its says so in owners manuals :)  

I used Mitsubishi as an example to make a point. Members who have replied above have confirmed it's the same with their Suzuki and Toyota as well. Most if not all other manufacturers also recommend that you maintain the same (or within a certain tolerance level like 1%) rolling diameter wheels on AWD vehicles. Having equal tyre pressure is part of maintaining equal rolling diameter. It's also not recommended to have staggered wheel sizes or a combination of worn and new tyres.

Also, Mitsubishi's AWC is in fact a dynamic AWD system. It has three drive modes where torque distribution is very different between each mode. 

Finally, the warning you're talking about when you have 5 passengers has nothing to do with AWD. It's the Tyre Pressure Monitoring System telling you that you need to maintain max load pressure. It even happens on front/rear wheel drive vehicles. 

1 hour ago, kmeeg said:

I would simply follow the info on the tire info tag on the driver side door..

IMG_0911 (2).jpg

This is the right thing to do. If that's the tyre pressure chart on your car, then it's obvious that they've stated equal tyre pressure all round. If you read the owner's manual, you should be able to find information on how you should maintain equal rolling diameter as well. 

Edited by Davy

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Posted (edited)

Hi Davy.

 

There we go....

https://www.carsguide.com.au/land-rover/range-rover-velar/tyre-pressure

I checked the disco etc and also they also recommend the same in door label. Just because your mitsubishi (even Suzuki and Toyota etc) needs same tire pressure on all its bad idea to make it a fact for all vehicles in the world :D 

Edited by Junkfriend

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Posted (edited)
1 hour ago, Junkfriend said:

Hi Davy.

 

There we go....

https://www.carsguide.com.au/land-rover/range-rover-velar/tyre-pressure

I checked the disco etc and also they also recommend the same in door label. Just because your mitsubishi (even Suzuki and Toyota etc) needs same tire pressure on all its bad idea to make it a fact for all vehicles in the world :D 

Let me take your own example. In the link you've shared, the recommended tyre pressure for 1 to 3 passengers is same all round (34 PSI in all but one case where it's 61). So for a normal load, it proves the point I'm trying to make. :) Further, if you take any two random tyre sizes from the list and compare the overall diameter of the wheel, you will find that there is no more than 1% variation between each pair. 

The reason why you need to have a higher tyre pressure at the rear when you have more passengers (in this case 3 to 5) is because the tyre's overall diameter is reduced by the additional weight. So the rears need more pressure to maintain equal rolling diameter with the front two tyres. If you look at the link you've sent again, you will notice that it's always the rear that has a higher recommended tyre pressure because the additional passengers (and probably luggage) puts weight on the rear tyres.

I accept that when I said you should maintain equal tyre pressure, I should have been more clear and mentioned that for a normal load  and that it should be equal rolling diameter and not necessarily tyre pressure. Still doesn't make my statement "absolutely wrong".

As I've mentioned in my initial post, if the system is electronically operated, it does hundreds of calculations per second to determine the amount of torque to be sent to each wheel. It does so by monitoring the signal from each wheel speed sensor. If you have one wheel with smaller diameter, then the speed sensor will pick up a higher speed signal from that wheel and assume that the wheel is slipping and divert torque to the other wheels to keep the vehicle stable. This is why all wheels need to have equal rolling diameter. 

Finally, I have not based this on just my Mitsubishi or the posts made by others. It's just physics and mechanics. And to my knowledge, physics applies equally all over the world. So all manufacturers are bound by it. :) 

 

Edited by Davy

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Posted (edited)
1 hour ago, Junkfriend said:

Hi Davy.

 

There we go....

https://www.carsguide.com.au/land-rover/range-rover-velar/tyre-pressure

I checked the disco etc and also they also recommend the same in door label. Just because your mitsubishi (even Suzuki and Toyota etc) needs same tire pressure on all its bad idea to make it a fact for all vehicles in the world :D 

Didn't you do the same the other way around ? You pretty much said having the same tire pressure in all the tires is not to be done when you said "That's absolutely wrong". In fact what you did has more of a detrimental effect since the case you site is more of an exception than the norm (considering most of the vehicles the OP is considering are the norms, them being the Toyotas and the Mitsus, etc...

So..instead of turning this in to a who said what match...can we summarize by saying

"it is important to maintain constant tire pressures because it effects the longevity and possibly the performance of the system.  Some vehicles require all tires to be the same pressure whilst under certain conditions different tire pressures maybe recommended. so its best to check the manufacturers' recommendations" ?

EDIT : I really didn't check the link....but still what I say stands...

Edited by iRage

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All depend on the vehicle, example Porsche Macan is full time 4WD with 20:80 torque split between front and rear, has different tire width front / rear, different pressure front/ rear

CRV 4WD, electronic activation when front wheels slip requires to maintain identical tires all around, pressure same for all wheels

This is what Porsche Manual says

Initially, new tires do not provide their full grip.

  • You should therefore drive at moderate speeds during the first 120 miles (200 km) to extend the service life of the tires and achieve full performance capability.

  • Only tires from the same manufacturer and with the same specification code (e.g. "N0," "N1," etc.) may be mounted on the vehicle.
  • Before mounting new tires, inquire about their current approval status: Contact an authorized Porsche dealer. e Use only tire makes tested and approved by Porsche.
  • The difference in tread depths on one axle must not exceed 30%.
  • Always replace both tires on one axle to avoid any unnecessary effect on driving behavior due to varying tread depths.
  • Only authorized Porsche dealers may install tires.
    Visit a qualified specialist workshop. Porsche recommends an authorized Porsche dealer, as they have trained technicians and the necessary parts and tools.
  • Adjust your driving style to the altered handling behavior.

  Go with the manufacturer specifications /  recommendation they know the vehicle best 

 

 

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16 minutes ago, Davy said:

Let me take your own example. In the link you've shared, the recommended tyre pressure for 1 to 3 passengers is same all round (34 PSI in all but one case where it's 61). So for a normal load, it proves the point I'm trying to make. :) Further, if you take any two random tyre sizes from the list and compare the overall diameter of the wheel, you will find that there is no more than 1% variation between each pair. 

The reason why you need to have a higher tyre pressure at the rear when you have more passengers (in this case 3 to 5) is because the tyre's overall diameter is reduced by the additional weight. So the rears need more pressure to maintain equal rolling diameter with the front two tyres. If you look at the link you've sent again, you will notice that it's always the rear that has a higher recommended tyre pressure because the additional passengers (and probably luggage) puts weight on the rear tyres.

I accept that when I said you should maintain equal tyre pressure, I should have been more clear and mentioned that for a normal load  and that it should be equal rolling diameter and not necessarily tyre pressure. Still doesn't make my statement "absolutely wrong".

As I've mentioned in my initial post, if the system is electronically operated, it does hundreds of calculations per second to determine the amount of torque to be sent to each wheel. It does so by monitoring the signal from each wheel speed sensor. If you have one wheel with smaller diameter, then the speed sensor will pick up a higher speed signal from that wheel and assume that the wheel is slipping and divert torque to the other wheels to keep the vehicle stable. This is why all wheels need to have equal rolling diameter. 

Finally, I have not based this on just my Mitsubishi or the posts made by others. It's just physics and mechanics. And to my knowledge, physics applies equally all over the world. So all manufacturers are bound by it. :) 

 

haha I guess you still have to admit that you didn't know LR/RR/JLR AWD systems can have different tire pressures when you originally said "all AWD system needs to have same tire pressure"  based on your knowledge in Mitsubishi's and what others posted :D

 

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Posted (edited)
25 minutes ago, kush said:

All depend on the vehicle, example Porsche Macan is full time 4WD with 20:80 torque split between front and rear, has different tire width front / rear, different pressure front/ rear

CRV 4WD, electronic activation when front wheels slip requires to maintain identical tires all around, pressure same for all wheels

 

Exactly!

 

Quote

You should therefore drive at moderate speeds during the first 120 miles (200 km) to extend the service life of the tires and achieve full performance capability.

Thanks for the tip machan, I didn't think of that! I was driving something very new  / very fast in the other day and tuk tuk dude cut in and brakes didnt work that well and I almost crashed.  

Edited by Junkfriend

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12 minutes ago, Junkfriend said:

haha I guess you still have to admit that you didn't know LR/RR/JLR AWD systems can have different tire pressures when you originally said "all AWD system needs to have same tire pressure"  based on your knowledge in Mitsubishi's and what others posted :D

 

To me it seems like Land Rover is doing exactly what the rest of the world is doing - sticking to equal rolling diameter. But they're doing so by varying tyre pressure. I already said that I was wrong when I said "equal tyre pressure". It should obviously be equal rolling diameter. You could have corrected me when you saw it - that would have been the gentlemanly thing to do. 

There is no denying that sticking to manufacturer's recommendation is what should be done. By adhering to the manufacturer's tyre pressure chart, what you're essentially doing is maintaining equal rolling diameter.

To further my point on maintaining same sized tyres on AWD vehicles, read the content in the links below:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=18&

https://www.souzastireservice.com/tires-101/tire-matching-awd-4wd.aspx

  • Thanks 2

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5 hours ago, Davy said:

To me it seems like Land Rover is doing exactly what the rest of the world is doing - sticking to equal rolling diameter. But they're doing so by varying tyre pressure. I already said that I was wrong when I said "equal tyre pressure". It should obviously be equal rolling diameter. You could have corrected me when you saw it - that would have been the gentlemanly thing to do. 

There is no denying that sticking to manufacturer's recommendation is what should be done. By adhering to the manufacturer's tyre pressure chart, what you're essentially doing is maintaining equal rolling diameter.

To further my point on maintaining same sized tyres on AWD vehicles, read the content in the links below:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=18&

https://www.souzastireservice.com/tires-101/tire-matching-awd-4wd.aspx

I guess it make sense now

Macan specifies 3-4 psi higher pressure to the rear wheels  likely to compensate for the rear biased drive

30% difference in thread depth between axles works out to 0.5% in rolling diameter which may be within the tolerance of the AWD system.

 

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4 hours ago, kush said:

I guess it make sense now

Macan specifies 3-4 psi higher pressure to the rear wheels  likely to compensate for the rear biased drive

30% difference in thread depth between axles works out to 0.5% in rolling diameter which may be within the tolerance of the AWD system.

 

The tire sticker I posted was from a 4wd vehicle. So unless I select 4H or 4L the vehicle is powered by the rear wheels all the time. But mine says to run same tire pressure. I would say;

1. Simply follow what manufacturer specified.

2. I would never over inflate from the spec so it would effect braking distance.

3. I would never under inflate from the spec so I would get bad gas mileage and premature tire damage.

** The only time I would run on relatively low tire pressure is on a off-road situation where I need a bigger foot print so I won’t get stuck on sand or mud. But I try to avoid it to my best. Tires are damn expensive and I have many other expenses to think of..?

Bottom line what I want to tell was keep the tire pressure as specified by manufacturers. Not from some article on Facebook or Google. Try not to buy cars that have different tire sizes front and rear so that you can do tire rotation without any problem.

 

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Posted (edited)
12 hours ago, kmeeg said:

Bottom line what I want to tell was keep the tire pressure as specified by manufacturers. Not from some article on Facebook or Google. Try not to buy cars that have different tire sizes front and rear so that you can do tire rotation without any problem.

 

Yhh this would be the best route to take. Im almost all cars recommended pressure is shown in the door sticker and in  main display in all new cars. Just read that and you are fine. And yes it would really help if you under inflate on sand probably between 15-25 PSI, to 15 PSI only if you have loads of $$$ to buy rubber ;)   

Edited by Junkfriend

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16 hours ago, kush said:

30% difference in thread depth between axles works out to 0.5% in rolling diameter which may be within the tolerance of the AWD system.

 

gud point there :)

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13 hours ago, kmeeg said:

Try not to buy cars that have different tire sizes front and rear so that you can do tire rotation without any problem.

 

Miss out on all the fun cars

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