uTire
uTire promises to deliver realistic tire deformation to any wheel in Unity3D. In addition to the built in Wheel Collider it also supports the Vehicle Physics Pro Wheel Collider and the WheelController 3D which is included in NWH Vehicle Controller.
When I write this it only have 6 ratings, but they’re all 5 star ratings and I do agree with that.
uTire supports all of Unitys render pipeline but have only tried it with the built-in render pipeline.
Installation
Installation is pretty simple, just be aware that it depends on Naughty Attributes so you must install that first.
It also have a package dependency to the jobs system which caused a minor problem. With Unity 2021.3.6f I got a compile error for the Jobs system, but that was easily resolved by upgrading Jobs to the latest version.
Documentation
Documentation is included in a PDF and I don’t have much to say about it. It’s short and to the point, it’s what you expect and what you want.
Demo scenes
uTire includes two demo scenes. There’s the utire_example that shows the capabilities of the tire deformation. It’s nice to see that it handles deformation from any direction, and from multiple directions.
Next there’s the utire_dynamic_example where you can see how the tire deformation is not only visual but also capable of altering the wheel collider itself. I find this feature quite interesting and while I won’t have time to go into the details of that today it’s something I hope to explore further in the future.
Components
uTire consists of two components. First there is a script that handles the visual deformation. This has no effect on the wheel colliders, or the behavior in any way. So it can be added to any project without breaking anything. There are some settings for quality, what shader to use, and what layers collisions should be checked against. Great if you don’t want the wheels to collide with the vehicle itself.
In addition to the visual part there’s a script that attaches to the wheel collider and alters the colliders radius depending on the wheels deformation. In my short and limited experience this seems to work well but requires some care to setup since altering the colliders to much can lead to unexpected behavior. Something I’d say is always the case with wheel colliders. They’re quite delicate creatures.
Usage in a real project.
And now to the fun part. Using it in a real world project. Luckily I have an off road game I’ve been working on so let’s bring some tire deformation into that. The project uses NWH Vehicle Controller with Wheel Controller 3D so this will test that integration as well.
Visual deformation
The integrations for Wheel Controller 3D and VPP Wheel Collider are included as an additional package with uTire. You’ll find it in the integrations folder. Once it’s installed it’s not in the same folder structure as the rest of uTire, but in a 2SD folder directly on the Asset level. The reason for that is explained in the documentation so it’s the expected location.
First I just added the uTire runtime to the wheel meshes and the result was quite good without tweaking anything.
As you can see in the screenshot this wheel have separate materials for the rim and the tire. I only added the uTire material to the tire.
I didn’t find any setting to change the deformation. Not sure if I missed it or if it’s not there. There’s however a setting for air pressure once you install the dynamic component.
Dynamic component
The dynamic component, in this case uTire V2 Wheel Controller, is added to the same game object as the actual wheel controller/collider. It will dynamically change the wheel controller depending on tire deformation. It also have a setting for air pressure that allows you to control how much the tire is deformed.
I found the default setting of 0.5 to be way to low for my 1800 kg car.
As you can see the rock also cuts trough the rim, but that’s only because I didn’t adjust the rim size.
Once I tweaked the settings to fit my car everything looks great.
It looks good when driving as well and the tire deforms as expected when passing over rocks and other objects.
Summary
I’m happy with the results and the setup was very simple. I had to make sure it collided with my terrain layer, then adjust rim size and air pressure. That was it. I doubt setup could be easier. Results are good and I didn’t notice any performance impact.
Available in the asset store with a price tag of $29.99 I’d say it’s worth the money. But given that it’s not essential, and easy to add to an existing project, it might be worth to wait for it to be on sale.
