Bigger tires and the limits of an SYA KIT

**DiscoDB** · 30th May 2025, 08:05 AM

Originally Posted by discomatt69

Never seen these kits , how do they lift the car without increasing bag pressure?
to achieve that do they have a spacer under the bag or something?
just moving sensors, changing rods or bump stops doesn’t change height without changing airbag pressure
is it a body lift?

The SYA kit is basically a spacer which sits between the top of the airbag and the chassis/body. So you achieve a lift at the same bag/shock extension.

The maximum lift is still limited due to the geometry of the suspension/drive train hence they also come with straps to stop over-extending when you pick up a wheel off the ground.

The maximum lift achieved appears to be no greater than what we can achieve say using the GapIID tool to reset the height, but the benefit is it gives the body extra lift when on the bump stops (which also get spacers to raise the height) so you can fit larger tyres with less concern about dropping the body onto the wheels when the air suspension fails.

This type of mod seems to be popular in North America where some very extreme rocky trail tracks are tackled and you want as much lift as you can get. I can’t imagine many of these kits have been sold into Australia. Never seen a post here on these before, but they get discussed a lot on Landroverworld.org.

**loanrangie** · 30th May 2025, 08:06 AM

Originally Posted by Trist

Do you mean the kind of lift rods that increase pressure and preload? I agree those can be problematic, as I have mentioned in my Post.
What I’m referring to is the SYA kit that physically repositions the sensor bracket and bump stops, so the vehicle rides higher with lower air pressure.
It’s not like a +2” static rod lift. Curious if you’ve seen the difference between these approaches in practice?

No not rods, electronic like llams/easy lift etc. You don't need the SYA kit if all you want is 1.5" of lift.

**DiscoJeffster** · 30th May 2025, 08:40 AM

Originally Posted by Graeme

Air-spring height is achieved using increased air volume, not pressure. Pressure increases with added weight.

Not 100% correct. Pressure also increases as does volume as the bag expands. I get your point but there is an increase in pressure as well.

**DiscoDB** · 30th May 2025, 10:34 AM

Originally Posted by Graeme

Air-spring height is achieved using increased air volume, not pressure. Pressure increases with added weight.

I ran +40mm height for a while (when having suspension fault issues which would see the car regularly drop to a lowered height) and I very much liked how it “firmed” up the ride with the extra volume of air.

**DiscoDB** · 30th May 2025, 10:50 AM

Originally Posted by Trist

My goal here is more of a static solution: I want to retain full range of air suspension without stressing struts long-term. Balance the disco's comfortable looks, geometry and off-road ability.
Not at all aiming for extreme clearance or rock-crawling, it's just not the cars habitat or purpose.
Belgium isn’t wild, but our convoy terrain includes a lot of mud, wet forestry and deep ruts that benefit from a 33” + sidewall.

If the aim is just to run the largest tyres you can and not for extreme rock crawling, I would be more inclined to program a 40mm lift with the GapIID tool to reset the normal height, and then look into just adding bump stop height extensions so when the suspension faults it doesn’t run the risk of the body sitting on the wheels.

The largest tyre size I have read anyone running on the D4 on this forum was 32” (275/65R18).

**Trist** · 4th July 2025, 10:06 PM

Originally Posted by DiscoDB

If the aim is just to run the largest tyres you can and not for extreme rock crawling, I would be more inclined to program a 40mm lift with the GapIID tool to reset the normal height, and then look into just adding bump stop height extensions so when the suspension faults it doesn’t run the risk of the body sitting on the wheels.

The largest tyre size I have read anyone running on the D4 on this forum was 32” (275/65R18).

Would a 285/65/18 work, only one available in my country...

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