Lee says in the letter to Alison Redford that horses are injured or killed in the races every year.
"I love touring Canada, and our Calgary fans are among the roughest and toughest. But I've heard about some unwilling participants in an annual local event much harsher than a Motley Crue show — the horses killed year after year in the chuckwagon races at the Calgary Stampede," Lee writes to Redford, who is also a Calgary MLA.
"The only way to make these races safe is to cancel them. There was a time when cowboys respected their horses, instead of riding them to death just to show off for a crowd."
The letter was written on the behalf of People for the Ethical Treatment of Animals, an animal rights advocacy group that is a longtime critic of the chuckwagon races.
"I learned from my friends at PETA that despite new rules to make the races safer last year, three horses had to be euthanized after crippling injuries when their wagons collided," wrote Lee.
"The horses forced into the chuckwagon races die of heart attacks, broken necks, broken legs and other injuries. It'd be easy to get off on western tradition without this bloody spectacle.
"Dude, it's the Old West, not ancient Rome!"
There was no response from the premier's office. But an official with Alberta Agriculture said the province would never ignore any signs of abuse.
"It falls within our portfolio and we do take treatment of animals very seriously, so we've worked very closely with the Calgary Stampede and we continue to do that," said Cathy Housdorff.
The Stampede's animal care is of a high standard and the government has no intention of shutting down the chuckwagon races, she said.
"Not at this point of time. No."
The event is one of the most popular at the Stampede. It invariably sells out each year, but concerns over animal welfare have become more prevalent over the last decade and were magnified in 2010 after six horses died.
A Stampede official said Lee doesn't know all the facts.
"We don't think Tommy Lee is a large animal expert," said Doug Fraser.
"We would urge him and anybody who has that feeling to actually talk to the drivers themselves about the care and well-being that they provide to their animals."
In 2011, the Stampede adopted new rules for rodeo events and chuckwagon races to try to provide more protection for both human and animal participants.
"All we can do is repeat that our approach to care for the performance horses that are brought to Stampede Park every year has always been aggressive and based on science," said Fraser.
Canadian-born celebrity Pamela Anderson, who was once married to Lee, spoke out against the chuckwagon races last year and also sent a letter to Redford on behalf of PETA.
A PETA spokesman said Lee heard about chuckwagon racing from Anderson and it made sense to take advantage of Motley Crue's concert in Calgary on Monday to issue a pre-emptive strike.
"Usually you hear about the disasters at the chuckwagon races and all the horse injuries after the fact," said PETA vice-president Dan Mathews.
"We thought the fact that Tommy, who's a longtime PETA spokesperson, is in Calgary with Motley Crue before the event that he should give everybody a heads-up and call on the premier to act responsibly and cancel the chuckwagon races."
Lee was travelling with his band and was unavailable for an interview. He did say in his letter that he'd love to have Redford as his guest at the concert.
Mathews said the sport appeals to the worst in people.
"The chuckwagon races really just appeal to people's dark side, masqueraded as drunken fun," he said.
"It's bloodlust and the people who are there hope to see a crash and they might as well set up cheering stands at DUI crashes or in an emergency room."
This year's Stampede runs July 5-14.