I recently purchased a new Isuzu MU-X in Chonburi.

Before taking delivery, I upgraded the wheels from the standard 17" to Isuzu 20" wheels.

The problem I'm finding is when doing a u-turn or a 90° turn, the steering does not self-centre .

The tracking has been checked and supposedly is OK.

Any ideas?

Dunno, but I bet the ride is cr@p....😵

Try increasing tyre pressure 

Title changed. 

 

Tip: you might want to check what your insurance has to say about you fitting non- standard size wheels.

 

Horrible if you had an accident and they refused to help/pay.

 

Just a suggestion.

 

3 minutes ago, transam said:

Dunno, but I bet the ride is cr@p....😵

 

555

 

 

9 minutes ago, JBChiangRai said:

Try increasing tyre pressure 

What he said 

 

You'd want to be running the fronts at ~ 38psi IMO.

My favourite AI (Bard) says: -

 

Quote

There are a few possible reasons why your Isuzu MU-X's steering is not self-centering after upgrading the wheels to 20".

• Incorrect wheel offset: The wheel offset is the distance between the mounting surface of the wheel and the center of the wheel. If the offset is too high or too low, it can cause the steering to be more difficult to control and less likely to self-center.
• Alignment issues: If the wheel alignment is not correct, it can also cause the steering to be off-center and less likely to self-center.
• Suspension problems: If there are any problems with the suspension, such as worn ball joints or tie rods, it can also cause the steering to be off-center and less likely to self-center.

If you have already had the tracking checked and it is OK, then the most likely cause is the wheel offset. The standard 17" wheels on the Isuzu MU-X have a negative offset, while the 20" wheels you have upgraded to may have a positive offset. This will cause the wheels to stick out further from the vehicle, which can change the steering geometry and make it more difficult to control the vehicle.

To fix the problem, you will need to either change the wheels back to the standard 17" wheels or install spacers to change the offset of the 20" wheels. It is important to note that changing the offset of the wheels can affect the handling of the vehicle, so it is important to have the vehicle checked by a qualified mechanic before making any changes.

Here are some additional things to check:

• Make sure that the tire pressure is correct. If the tire pressure is too low, it can cause the tires to roll over, which can make the steering feel loose and off-center.
• Check the power steering fluid level. If the fluid level is low, it can cause the steering to be difficult to control and less likely to self-center.
• Check the steering wheel for any play. If the steering wheel has play, it could be a sign of a problem with the steering rack or other steering components.

If you have checked all of these things and the steering is still not self-centering, then it is best to take the vehicle to a qualified mechanic to have it diagnosed and repaired.

 

3 minutes ago, McTavish said:

What he said 

 

You'd want to be running the fronts at ~ 38psi IMO.

Then the ride will definitely be cr@p........🤭

8 minutes ago, transam said:

Then the ride will definitely be cr@p........🤭

Fat lot you know about the subject, KhunT 

 

I agree with your statement re the fitment of 20" wheels making for a crap ride and whilst the higher pressure may alleviate the steering problem it will not make the ride any softer, that's a given.

1 hour ago, McTavish said:

Fat lot you know about the subject, KhunT 

 

I agree with your statement re the fitment of 20" wheels making for a crap ride and whilst the higher pressure may alleviate the steering problem it will not make the ride any softer, that's a given.

Seems by your second para I was right............😉

 

Wheel and tyre dimensions are dialled into the suspension at factory. if you put taller wheels with skinny tyres on a ride that from factory had smaller wheels and taller tyre sidewall, the ride will be cr@p....

 

As I recall, my ol' 4x4 Vigo had 16" wheels with 265x70x16 tyres, with 29psi all round loaded or unloaded.. 20" with skinny tyres and 38 PSI will be 'orroble, must wear a crash hat for head to roof contact.......😁...

30 minutes ago, transam said:

Seems by your second para I was right............😉

 

Wheel and tyre dimensions are dialled into the suspension at factory. if you put taller wheels with skinny tyres on a ride that from factory had smaller wheels and taller tyre sidewall, the ride will be cr@p....

 

As I recall, my ol' 4x4 Vigo had 16" wheels with 265x70x16 tyres, with 29psi all round loaded or unloaded.. 20" with skinny tyres and 38 PSI will be 'orroble, must wear a crash hat for head to roof contact.......😁...

Quite right, T. 

Where you're mistaken is in reference to the OP's 'steering' problem which is what I was addressing.

This is something I have dealt with many times with service customers in UK.

The steering self-centering (technically 'returnability') and steering 'feel' depends principally on steering castor angle and scrub radius (the radius of the arc that the centre of the tyre contact patch describes about the projected pivot axis). The scrub radius, in turn, depends upon the wheel offset. So changing wheel offset significantly away from the chassis specification can cause problems. Maximum of +/- 5mm away from spec is the rule of thumb.  I bet your 20" wheel offset is outside spec.

Unfortunately a lot of drivers buy wheels/tyres solely based on appearance. Large diameter wheels with very- or ultra-low profile tyres are OK on a racing circuit but a bad idea on a vehicle used on normal roads, especially in Thailand. The tyre sidewall is part of the suspension system, protects the wheel from shock loads (potholes etc) and also allows progressive handling through tyre deformation (slip angle) in cornering.  What you see in the workshop is a lot of vehicles fitted with very low profile tyres have buckled wheels.......

My advice is to try to get a refund on the 20" wheels and go back to standard.

On 10/31/2023 at 2:17 PM, CharlieH said:

Title changed. 

 

Tip: you might want to check what your insurance has to say about you fitting non- standard size wheels.

 

Horrible if you had an accident and they refused to help/pay.

 

Just a suggestion.

 

 

OP says they are Izuzu 20" wheels ( MUX I assume) and fitted pre-delivery.... Wont be any insurance issues.

 

The issue will be castor settings... I'd be taking it back to Izuzu, they fitted them !

 

D-Max

• Wheel - 17 x 7 +33 offset
• Tyre - 255/65R17

Mu-X

• Wheel - 20 x 7.5 +33 offset
• Tyre - 265/50R20

 

Not enough difference between the two tyres to be causing any issue.

 

 

Firstly, I'd be astonished if a vehicle coming straight from the factory is out of tolerance on caster - and tolerance is usually pretty wide (I would think 2-4 degrees on this vehicle).  Secondly, he says he's already had wheel alignment checked.   I'd be checking those wheels out very carefully. Are you sure the dealer has fitted genuine Isuzu wheels?

As a side issue, be aware that this generation of MUX/DMAX and Mazda badged equivalents have rather poor front suspension geometry. Front toe changes considerably with suspension deflection leading to 'bump steer' and quite heavy front tyre wear.

4 hours ago, HauptmannUK said:

As a side issue, be aware that this generation of MUX/DMAX and Mazda badged equivalents have rather poor front suspension geometry.

Any generation IMHO. Just about the only thing I don't like about my DMAX (coming up 14 years old) is the crap turning circle. Whilst not suffering the steering issues mentioned here, I find I have to keep an eye on the front tyre wear, as the nearside seems to lose tread quicker, probably because of constant U-turns.

On 11/2/2023 at 2:33 AM, HauptmannUK said:

This is something I have dealt with many times with service customers in UK.

The steering self-centering (technically 'returnability') and steering 'feel' depends principally on steering castor angle and scrub radius (the radius of the arc that the centre of the tyre contact patch describes about the projected pivot axis). The scrub radius, in turn, depends upon the wheel offset. So changing wheel offset significantly away from the chassis specification can cause problems. Maximum of +/- 5mm away from spec is the rule of thumb.  I bet your 20" wheel offset is outside spec.

Unfortunately a lot of drivers buy wheels/tyres solely based on appearance. Large diameter wheels with very- or ultra-low profile tyres are OK on a racing circuit but a bad idea on a vehicle used on normal roads, especially in Thailand. The tyre sidewall is part of the suspension system, protects the wheel from shock loads (potholes etc) and also allows progressive handling through tyre deformation (slip angle) in cornering.  What you see in the workshop is a lot of vehicles fitted with very low profile tyres have buckled wheels.......

My advice is to try to get a refund on the 20" wheels and go back to standard.

Perhaps I didn't explain properly in my original post

 

Isuzu make three specs in their MU-X model.  The base (which I have bought) has 17" wheels, the mid 18" and the top 20".

I up-graded (mainly because they had Bridgestone tyres, as opposed to Dunlop), but all three specs are the same car, same engine, but differing slightly in seating aerials, and electrical refinements.

I hope this clarifies the matter..

On 11/2/2023 at 10:37 AM, Eff1n2ret said:

probably because of constant U-turns.

 

You wouldn't be a politician would you?

30 minutes ago, meuok said:

Perhaps I didn't explain properly in my original post

 

Isuzu make three specs in their MU-X model.  The base (which I have bought) has 17" wheels, the mid 18" and the top 20".

I up-graded (mainly because they had Bridgestone tyres, as opposed to Dunlop), but all three specs are the same car, same engine, but differing slightly in seating aerials, and electrical refinements.

I hope this clarifies the matter..

And probably different suspension with different wheels, I would have thought.🤔

17 hours ago, transam said:

And probably different suspension with different wheels, I would have thought.🤔

No, mate.  According to the spec brochure, the suspension is the same on all three models..

17 hours ago, transam said:

And probably different suspension with different wheels, I would have thought.🤔

 

If the  vehicle did have different suspension (which it does not) how would changing wheels (that have the same offset and rolling diameter) create a (what appears to be)  castor issue ?

2 hours ago, Ralf001 said:

 

If the  vehicle did have different suspension (which it does not) how would changing wheels (that have the same offset and rolling diameter) create a (what appears to be)  castor issue ?

Gawd, suspension includes the springs and shocks..........🙄

2 hours ago, meuok said:

No, mate.  According to the spec brochure, the suspension is the same on all three models..

Including springs....?

I wouldn't know.............😋

2 minutes ago, transam said:

 

I wouldn't know.............😋

 

A reoccurring theme.

4 minutes ago, transam said:

Gawd, suspension includes the springs and shocks..........🙄

What is the difference with springs and shocks between the Mu-X Range and how does this affect steering castor ?

1 minute ago, Ralf001 said:

What is the difference with springs and shocks between the Mu-X Range and how does this affect steering castor ?

No idea, tell me......?    😉...........🤭

Just now, transam said:

No idea

A reoccurring theme.

1 minute ago, Ralf001 said:

A reoccurring theme.

No idea, I asked you, tell me/us....?

 

3 hours ago, transam said:

No idea, I asked you, tell me/us....?

 

 

You are the one banging on about different suspension, not me.

 

Why do you involve yourself with subjects you clearly have zero knowledge of ?

8 minutes ago, Ralf001 said:

 

You are the one banging on about different suspension, not me.

 

Why do you involve yourself with subjects you clearly have zero knowledge of ?

So can't tell us, never mind..........😉