[Jeroen]

Originally Posted by adasisthefuture

With upgrade of Alloys to 21 inches, GC increases by 13mm i.e from 152 mm to 165 mm. In such a scenario, the suspension has to compress more, not less in my limited understanding as the GC is more than 152mm (165 mm to be precise) with 21 inch alloys and the system has to adjust the suspension downwards, not upwards if I have understood it correctly.
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Yes, I think we are saying the same.

I made this simple drawing (Because I don't do PowerPoint anymore

A very simple representation of your car. I choose trailing arms as part of the suspension. Whatever suspension you have, the principle remains the same.

The air suspension keeps a certain ride height. It measures by the angle of a suspension component versus a chassis component. This is the angle alpha.

When you mount larger tyres (middle image) the angle alpha remains the same, so the ride height increases (in your case with some 15mm).

If the air suspension system is adjusted for the larger tyre, it will lower the ride height back to its original value. The angle has become smaller (Beta is smaller than Alpha).

Your shock/springs/bellows need to compress (distance B is less than A). A better term to have used would have been, that the suspension components get shortened on their upwards-free travel.



Hope this helps

Jeroen

[adasisthefuture]

Originally Posted by Jeroen

When you mount larger tyres (middle image) the angle alpha remains the same, so the ride height increases (in your case with some 15mm).

If the air suspension system is adjusted for the larger tyre, it will lower the ride height back to its original value. The angle has become smaller (Beta is smaller than Alpha).

Thank you so much for the detailed response and taking the trouble to draw an image representation for me.

So in conclusion, what would be your final advice ? If I upgrade to the 21 inch alloys which I am doing to gain additional GC, will my ride height increase or will it remain the same ? The upgrade costs around 5 lacs so if it doesn't raise the ride height, it is not worth it. Thank you and sorry for the botheration.

[Jeroen]

Originally Posted by adasisthefuture

Thank you so much for the detailed response and taking the trouble to draw an image representation for me.

So in conclusion, what would be your final advice ? If I upgrade to the 21 inch alloys which I am doing to gain additional GC, will my ride height increase or will it remain the same ? The upgrade costs around 5 lacs so if it doesn't raise the ride height, it is not worth it. Thank you and sorry for the botheration.

See if you can get a better answer from Volvo. Alternatively, you could just stick the larger tires under and enjoy the extra ground clearance and not bother with the system update. Which means your speedo is going to off by a bit. I am not sure if other functions are affected by the update. I can imagine that even systems such as ABS and ESP and so on might be adjusted as well.

To be honest, without really understanding what the effects of larger tires are on the Volvo, with or without updating the system it is really not possible to give any meaningful advice.

Look for a dedicated Volvo forum, preferably in the USA, or maybe Facebook Group. The Americans tend to know a lot of these sort of details because they all love fiddling with their car.

You might also want to check what your owner manuals says? Does it say anything about different sizes of tires.

Good luck

Jeroen

[adasisthefuture]

Originally Posted by Jeroen

To be honest, without really understanding what the effects of larger tires are on the Volvo, with or without updating the system it is really not possible to give any meaningful advice.

Thank you once again. I looked at the Accessories section on Volvo's website wherein a small note below the Wheels section is provided. I am posting the note and the link below for your kind perusal. Thank you.

https://accessories.volvocars.com/en...rid)/Automatic

[Jeroen]

Originally Posted by adasisthefuture

Thank you once again. I looked at the Accessories section on Volvo's website wherein a small note below the Wheels section is provided.]

Well, it doesn’t a say anything about updating the suspension and or ride height!

You should be able to check it with the help of the dealer. Put the car on a flat surface, e.g. their workshop. Measure the height of the car on the four corners. Next, get them to reset the tire dimensions and see if those measurements have changed at all. If they did not, the tire setting doesn’t affect the suspension and your large tires should provide additional ride height.

You should make the measurements with the engine running as that usually affects the air suspension system.

Good luck.

Jeroen

[adasisthefuture]

Originally Posted by Jeroen

You should be able to check it with the help of the dealer.

Jeroen

Thank you so much once again for your kind response. I think checking with the dealer as suggested by you when the car and wheels arrive would only be an academic exercise as no dealer in India has these 21inch alloys in ready stock and they would order it only on advance payment from the customer. Once the alloys are upgraded, even if it does not increase GC, I will have to take it.

[Jeroen]

Originally Posted by adasisthefuture

Thank you so much once again for your kind response. I think checking with the dealer as suggested by you when the car and wheels arrive would only be an academic exercise as no dealer in India has these 21inch alloys in ready stock and they would order it only on advance payment from the customer. Once the alloys are upgraded, even if it does not increase GC, I will have to take it.

You don’t need the new wheels. You can do this test with the old/current wheels on the car!

With the current wheels, if adjust the tire size doesn’t change the ride height you are good to go. You don’t need to measure the ride height as such. Any distance between chassis and ground primer and after changing the tire dimension is good!


Jeroen

[Jeroen]

Originally Posted by adasisthefuture

Thank you so much once again for your kind response. I think checking with the dealer as suggested by you when the car and wheels arrive would only be an academic exercise as no dealer in India has these 21inch alloys in ready stock and they would order it only on advance payment from the customer. Once the alloys are upgraded, even if it does not increase GC, I will have to take it.

You don’t need the new wheels. You can do this test with the old/current wheels on the car!

With the current wheels, if adjust the tire size doesn’t change the ride height you are good to go. You don’t need to measure the ride height as such. Any distance between chassis and ground primer and after changing the tire dimension is good!


Jeroen

[dhanushs]

Originally Posted by adasisthefuture

Thank you so much for the detailed response and taking the trouble to draw an image representation for me.

So in conclusion, what would be your final advice ? If I upgrade to the 21 inch alloys which I am doing to gain additional GC, will my ride height increase or will it remain the same ? The upgrade costs around 5 lacs so if it doesn't raise the ride height, it is not worth it. Thank you and sorry for the botheration.

I cannot say conclusively how volvo has implemented their tech, but once the car is out of the factory, the only constant reference point for ride height would be the car itself (eg: frame). Having ground as a reference point for adjusting ride height would be highly unreliable and improbable coming from an OEM.

So I would presume changing the wheels wont affect the ride height calibration. This is further reinforced by the fact that the company manual supports tyre size change.

[adasisthefuture]

Originally Posted by dhanushs

So I would presume changing the wheels wont affect the ride height calibration. This is further reinforced by the fact that the company manual supports tyre size change.

Thank you for your kind response and advice. Do you mean that even after installing 21 inch wheels which would increase the GC by 13 mm, the system will bring the ride height down from 165mm (increased due to bigger wheels) to 152 mm (As with stock 18 inch wheels) ? Have I understood you correctly.

Thank you once again.

[Jeroen]

Originally Posted by adasisthefuture

Thank you for your kind response and advice. Do you mean that even after installing 21 inch wheels which would increase the GC by 13 mm, the system will bring the ride height down from 165mm (increased due to bigger wheels) to 152 mm (As with stock 18 inch wheels) ? Have I understood you correctly.
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I just realized something. I belief your Volvo S90 only has air suspension at the rear, is that correct?

Because if it does I don’t think the air suspension system will be affected at all by different wheel sizes. I.e. you would get your additional ride height clearance.

If the front wheels do not have air suspension, it means the rear suspension needs to remain identical position wise when swapping to larger wheels. Otherwise the car would not ride level anymore. As we already noticed the manual doesn’t mention the air suspension being affected by the wheel size setting in the system.

So if your Volvo only has self levelling rear air suspension you are probably good to go with the extra ride height!

Jeroen

[dhanushs]

Originally Posted by adasisthefuture

Thank you for your kind response and advice. Do you mean that even after installing 21 inch wheels which would increase the GC by 13 mm, the system will bring the ride height down from 165mm (increased due to bigger wheels) to 152 mm (As with stock 18 inch wheels) ? Have I understood you correctly.

Thank you once again.

No. I mean, if you increase the tyre size, the GC will go up and shocks will not compress and compensate. As it will not affect the car itself but the distance to the ground. However, assume you add a spacer to your strut, then it may level itself and compress down.

[adasisthefuture]

Originally Posted by Jeroen

I just realized something. I belief your Volvo S90 only has air suspension at the rear, is that correct?

Because if it does I don’t think the air suspension system will be affected at all by different wheel sizes. I.e. you would get your additional ride height clearance.


Jeroen

Thank you so much. I am indebted to you for this and the fact that you have given so much thought to the issue. As you rightly pointed out, the car has rear air suspension and if it compresses the rear, it would create imbalance in the front. I just looked at the brochure once again. Along with rear Air Suspension, it says "Four-C Chassis". I hope it doesn't have anything to do with the ride height.

Thank you so much once again.

[Jeroen]

Originally Posted by dhanushs

No. I mean, if you increase the tyre size, the GC will go up and shocks will not compress and compensate. As it will not affect the car itself but the distance to the ground. However, assume you add a spacer to your strut, then it may level itself and compress down.

The discussion has evolved quite a bit from this view. When changing to larger tires the system (ECU and probably a few other computers) needs to updated for this larger size. It will adjust for instance the speedo and steering to accommodate the larger wheel.

What remained unclear whether the air suspension would compensate for the larger wheels, in which case the ride height would likely not increase.

Never ever use spacers on air suspension as you will throw off the system completely! The system will adjust downwards automatically.

Jeroen

[adasisthefuture]

Relevant portion of the Volvo S90 Brochure mentioned Four-C Chassis along with Rear Air Suspension