Canadians are cashing in on the ultimate cross-border shopping deal by flocking south of the border to purchase their tires.

British Columbian cars make up 35 per cent of weekday business at Discount Tire in Bellingham, Washington, and up to 50 per cent on weekends.

Assistant Manager Larry Bradford said it's worth the time and money to go tire shopping in the U.S., especially if you drive a high-end car like a BMW or Mercedes.

"Especially in the newer vehicles -- 17, 18-inch packages -- they can see savings between $300 to as high as $600 or $700 on a set of four," he told CTV News.

North Vancouver driver Mike Lee said he made the decision to buy in America after doing comparison shopping around Vancouver.

"I looked online and did some research and the price that I was going to pay at Costco in Vancouver is almost $200 difference compared to coming out here to Discount Tire, which is really only a 45 minute difference," he said.

Some of the biggest savings are for high-end vehicles.

Bridgestone Turanza tires for an Audi A6 in Canada will cost $295 each, plus installation and disposal fees, plus an additional 12 per cent HST -- a total cost of $1,411.15 for a set of four.

The exact same tires in the U.S. sell for $956.52. Even after paying HST at the border that's a cost savings of almost $340.00.

There are downsides, including having to return south of the border to have your tires serviced in the future.

"They do have to come down and get that done, but what we're finding is they're down here, planning ahead and we take care of all their service work for them, their rotations and everything at that time," Bradford said.

If tires are made in North America you have to pay HST at the border but you don't have to pay duty because tires are exempt under NAFTA.

If the tires are made outside of North America, like China, you have to pay HST plus an additional seven per cent for duty beyond your duty-free limits.

If you don't declare your tires at the border and are caught the CBSA can seize the tires and your vehicle -- and you have to pay a penalty to get the car back.

Another option is having your tires shipped to a postal outlet just south of the border.

The Letter Carrier in Point Roberts, Washington, says Canadians ship 2,000 tires to its office every winter. The depot charges $5 per tire to store them there until you can pick them up.

Watch CTV News for a full report from Lynda Steele…

Have your say: Do you go to the U.S. for cross-border deals?