* USTR Kirk sees need to guard against world protectionism
* China spat over tires shouldn't escalate to trade war
* U.S., Brazil should deepen trade ties (Adds China tire dispute, comments)
SAO PAULO, Sept 16 (Reuters) - U.S. Trade Representative Ron Kirk said on Wednesday world economies need to stay on alert to prevent protectionism from hurting a nascent global recovery.
The world needs trade policies that open opportunities and markets, not shut them down, Kirk said at a speech to business leaders in Sao Paulo, Brazil's largest city and financial hub.
A U.S. decision last week to impose higher duties on tire imports from China for three years raised tensions with the Asian country, but shouldn't escalate into an all-out trade dispute, he added.
"We don't believe this need or should spark a trade war," Kirk said. "We have to have meaningful and fair enforcement of the (WTO) rules."
Kirk also said the U.S. and Brazilian governments should work to deepen trade relations between the two countries.
"There is so much more room for growth," he said. (Reporting by Luciana Lopez, Writing by Elzio Barreto, Editing by Jackie Frank)