When it comes to the rules of the road, most of us would like to think we know right from wrong.

But there are a host of regulations out there that most drivers, motorcyclists and pedestrians probably aren't even aware of — and many of them carry a serious cost.

WA's acting road safety commissioner, Teresa Williams, said every road user should be familiar with all the rules, no matter how seemingly minor, to ensure the safety of themselves and others while out on the road.

She said all the rules had all been developed for a good reason and hefty fines could be the least of your worries if you fall foul of them.

"It's not just about the penalty you pay, it's the greater price you can pay," she said.

Here's some of the little-known traps you can fall into on the roads.

Motorcyclists — tighten that helmet strap

Motorcyclists are vulnerable road users and as such there are many road rules and associated penalties that apply to them.

If you are caught riding without an "approved helmet" you can receive a hefty fine of $550 and four demerit points.

As one Perth motorcyclist found out earlier this year, this can even mean wearing your helmet with your strap too loose.

Julian Collis says he loosened his chin strap to talk to the officers who stopped him. ( ABC News: Supplied )

But heads-up — you'll also need to leave your pet at home.

Attempting to dink an animal on the handlebars will incur a $100 fine.

And whatever you do, don't let them steer. Riding "no hands" could also net you a $100 fine.

Have a sidecar? Make sure it's on tight as failing to secure your sidecar or carrying too many passengers or children younger than eight years old could mean a fine of $100 and up to three demerit points.

Pedestrians and cyclists need to watch out too

Despite how often you see them broken, there are rules against jaywalking and violating them could see you cop a $50 fine.

Ms Williams said it was important to emphasise these fines, as increasing numbers of distracted pedestrians looking down at their phones and wandering onto the road caused serious problems.

Cyclists not wearing their helmets could be fined $50.

But that is overshadowed by the penalty for not having a working bell or brake, which is as much as $100.

You definitely can't do this in Western Australia. ( Flickr: Skinny Casual Lover )

Tailgating in a car is dangerous enough as a cyclist, but if you get closer than two metres from the back of a car on your bike, you'll cop a $100 fine.

"It's their [cyclists and pedestrians] responsibility as well as everyone else's," Ms Williams said.

Not even Siri can help you text while driving

When it comes mobile phones, the message is pretty clear: Don't use them while driving on the road.

Hey Siri: You can't send texts while driving, even if you're using a voice-activated service. ( AAP: Julian Smith )

If you do, you're looking at a fine of $400 and three demerits points.

But did you know it is illegal to create, send, or even look at a text message, video message, email or similar text-based communication, even when the phone is secured in a mounting or voice-operated?

"You can only touch a mobile phone to receive and terminate a phone call if the phone is secured in a mounting affixed to the vehicle," Ms Williams said.

"We have had incidents of people watching movies. If you are doing something that is distracting you it could be dangerous," Ms Williams said.

Belt up, and this goes for your passengers too

Countless studies have shown the vital importance of seatbelts in a crash, but not wearing one can seriously impact your hip pocket as well.

As a driver, there's a hefty $550 fine and four demerit points for being unrestrained.

But it's even worse if your passenger fails to buckle up. That'll cost you $600 — and the fine gets higher for each passenger.

This would be an expensive trip in Western Australia. ( ABC News: Greg Nelson )

"The fine increases with every unrestrained passenger, and passengers will also be fined $550 for failing to belt up," Ms Williams said.

Similarly, don't let your mates ride on the back of your ute, unless you're happy to part with $550 and four demerit points. They will also cop a separate $550 fine.

While some fines may seem obscure, Ms Williams said the road rules and penalties were in place for a reason.

"It's not just about the fine or the penalty, because people can pay the ultimate penalty unfortunately — their life," she said.