At 8,600 miles, the OEM front tire looks to have 500-1000 safe miles left. The OEM rear tire looks much better and has perhaps 1,500-3,000 safe miles left. I've decided to spring for Michelin Pilot Road 3s. I would prefer not to replace both tires at once. Am I taking a (safety) risk by replacing the front tire first and then the rear tire 2,000 miles later?