Perth's congestion woes and soaring fuel prices will result in more motorcycle riders being badly injured or killed on our roads as more motorists are pushed on to two wheels, according to Police Commissioner Karl O'Callaghan.

Mr O'Callaghan, a motorcycle rider, said the only way motorcyclists could ensure they stayed upright and alive was being suspicious of all other motorists on our roads.

"You've got to be suspicious of everyone out there who is driving around, you just have to keep watching all the time," Mr O'Callaghan said.

"The only reason I've stayed upright for 40 years of motorcycle riding is because I've been suspicious of everyone driving a car when I'm riding a motorbike."

Department of Transport figures show the number of motorcycles registered in WA has increased 48 per cent in the five years since 2008, with 120,436 registered at the end of last year.

This year, 14 of the 68, or 20 per cent, road fatalities have been people riding motorcycles.

"We are going to see an upward trend because there are more and more motorcycles being sold and one of the things that will happen is as congestion in Perth gets greater, people are going to start taking to motorcycles and scooters because it is just more convenient," Mr O'Callaghan said.

"They may not have considered it before but the cost of fuel, the cost of parking and the very significant increase in congestion is going to push more and more people on to motorbikes and you are going to find more people getting injured.

"And bear in mind you don't have the protections on a motorbike when you get hit that you do in a car."

Traffic Supt Mick Emmanuel said on average deaths on motorcycles made up nearly 16 per cent of all road fatalities despite motorcycles comprising only 5 per cent of all vehicles on WA roads.

"You are four times more likely to be killed on a motorcycle than you are in a car," he said. "It's a statistic I think that needs to be known before one decides to jump on a bike and ride."

Road Safety Council chairman Murray Lampard said motorists needed to remember motorcyclists "have equal rights and access to our road network".