4wd Rims and Tyres
How often have you talked to a 4wd enthusiast about their 4wd rims and tyres? Have you managed to make head or tail of what they say?
Have you ever seen a post on a forum asking for advice about what 4wd rims and tyres to run? The strings of numbers that people come out with are sometimes harder to follow than the ideas of Sheldon Cooper from the Big Bang Theory!
If I said to you that “My 4wd rims and tyres are a set of 285/75/R16s on a 16 x 7.5 steel rim with a +10 offset” (which I don’t by the way) would that send you stark screaming crazy?
If that sounds like you then read on and maybe I can clear some of it up for you. Firstly, lets start with 4wd Rims.
4wd Rims Explained
So firstly lets start with the basics. There are essentially two types of 4wd rims; Alloy and Steel.
The difference between Alloy and Steel Rims
Alloy and Steel rims are pretty easy to tell apart. Most modern 4wd rims now days are alloy. With the movement towards soccer mums and urban four wheel drives that never leave the bitumen, alloy rims have more visual appeal. They’re usually silver and shiny and look nice. According to Drive.com.au and Jax Quickfit Tyres, the main differences between alloy’s and steelies are:
- Alloy rims are made of lightweight metal alloys (hence the name)
- Because they’re lighter, they have less rotational resistance and therefore allow the vehicle to accelerate faster
- Alloy wheels shed heat better than steel wheels
- Alloy rims tend to be stronger
- Alloy rims have a lower melting temperature.
- Alloys are usually much more expensive
Another thing to keep in mind when 4 wheeling, is that if you damage an alloy rim, then it may be more difficult to repair out in the bush. Or in fact at all. On the other hand, if your steel rim is dented or deformed, then you can generally tap (bash) it back into shape.
So what’s best for us 4wd enthusiasts? Well that’s up to you really. 4wd Action have compared alloy vs steel rims. The article goes into a bit more detail to help you make up your mind.
What does Stud Pattern mean
Very basically, the stud pattern of a rim is how many nuts you have to undo to change your tyre. Most 4wd rims have either 5 or 6 studs, or nuts, that hold them on. Understand? Pretty simple really, right?
Well there is actually more to it than just that. A stud patter is expressed as two numbers.
So for example, on a rim that has an even number of bolt holes, a stud pattern of something like 6 x 125 would mean that there are 6 bolt holes and the distance between the centres of opposite bolts is 125mm.
On a rim with an odd number of bolt holes, for example 5 x 125, there are obviously 5 bold holes. But the measurement of 125 is taken from the back side of one bolt hole, to the centre of the most opposite bolt hole. Confused? Take a look at the pictures. They’re worth a thousand words. Thanks to Wheel-Size.com.
6 bolt stud pattern – Measure from centre to centre
5 bold stud pattern – Measure from the back of one to the centre of the most opposite one
4wd Rim size
The size of your Rim is measured usually in inches and is made up of two parts. The diameter and the width. So in the example at the very top of this page, I mentioned a Rim size of 16 x 7.5. This means that the diameter is 16 inches, and the width is 7.5 inches. That’s not to difficult either right?
Rim offset is a measure, in millimetres, of the distance between the hub of your rim (where it actually mounts to your car) and the centre line of your rim. Why are diameter and width measured in inches, where offset is measured in millimetres? No idea. If you find out then please comment below!
So imagine you’re looking straight at your tyre as it’s rolling towards you. You’re looking at the tyre tread. Imagine a line drawn from top to bottom, splitting the tyre in two, length-ways. The offset is how far away your hub is from that centre line.
There are three kinds of offset.
- Positive offset – A positive offset means that your hub sits outside the centre line if your rim. Effectively this pulls your tyres back in towards your vehicle. It also makes the rim appear ‘flatter’ from the outside.
- Zero offset – A zero offset means that your hub sits exactly on that centre line of your rim.
- Negative offset – A negative offset means that your hub sits inside the centre line of your rim. So closer to your car. This effectively pushes your tyre out away from your vehicle giving your car a wider stance. Your rim will appear more ‘bucket-like’. Or hollow.
The image to the right shows this perfectly. Note that the right hand side of each rim in the picture is the outer side. The one that you’d be able to see if it were on a car.
That basically explains 4wd Rims for you. Hopefully you’re a little less confused about the whole thing now. If I say to you that “I run a set of 285/75/R16s on a 16 x 7.5 steel rim with a +10 offset”, at least you’ll be able to decipher half of it now.
Take a look at my article about Tyres. Then you’ll be a full bottle!
*Featured image – Cooper Tyres Prado – Fraser Island