Colorado drivers won’t be required to get snow tires to drive on Interstate 70 next winter, after all. The state Senate voted yesterday to deflate a proposal to require motorists without four-wheel drive to use snow tires or carry chains or cables during winter months on the state’s main east-west highway. Senators amended the bill so that transportation officials would study the question for another year. The version now heads to the House, where members of both parties are skeptical about the change. The proposal had the backing of Colorado’s ski industry, which said that motorists using improper tires cause accidents that lead to costly traffic snarls. Commercial truckers also supported the chain requirement, which already applies to them. But Senate Republicans considered the requirement too much for noncommercial drivers.