Five-year-old cancer survivor Tiana Gray at the wheel and horn of a big rig.

A "beautiful convoy" of 70 big rigs promises to be quite a sight this Sunday.

The trucks are taking part in the biennial Professionals' Big Rig Ride in support of the Child Cancer Foundation, offering rides around Palmerston North streets for just $2 a head.

Convoy co-ordinator Derryn Hughes says the trucks make an impressive spectacle as they arrive en masse along with a helicopter, at the Railway Land at 10am. There the community rallies not only with rides, but with stalls, face-painting, raffles, auctions and prizes.

Child Cancer Foundation Tiana Gray has been in the cancer wars.

This week, drivers, including Turbos lock Fraser Stone, will be cleaning and polishing their rigs in readiness for the big day.

"We have some amazing prizes; local businesses and the truckies have been incredibly generous. It's been really humbling," Hughes said.

Among the prizes is a flight in a World War II Harvard, a helicopter flight, three hot laps with racing driver Greg Murphy, and a signed Liverpool football shirt.

The proceeds go to local families who have children coping with cancer and who need to spend time in Auckland's Starship hospital, putting a strain on family finances and resources.

The first Big Rig Ride took place in 2004 for Manawatu flood victims, with all subsequent events for the Child Cancer Foundation.