Originally Posted By: Jetronic
Are you sure they didn't say +7°C? As that's the generally accepted cutoff to switch to winter rubber here...
From BFG/Michelin
Quote:
First, I'd like to share that BFGoodrich (UHP) Sport Summer tires use tread compounds that are optimized for maximum dry and damp grip in temperate conditions. As the temperature of the compound nears freezing, the grip level of the tire begins to degrade. Michelin does not recommend using UHP Sport Summer tires when tire temperatures drop below 40°F (5°C) or on snow and ice.
To answer your question about the temperature, at tire temperatures below 20°F (-7°C) Michelin UHP Sport Summer tires may develop surface cracks in the upper sidewall and tread area if flexed. Do not use, roll, or drop MICHELIN UHP Sport Summer tires with temperatures below 20°F (-7°C). If the tires have been cooled to 20°F (-7°C) or less, let them warm up in a heated space to at least 40°F (5°C) before being installed or moving a vehicle on which they are installed. Do not apply heat or blow heated air directly on the tires. Always inspect tires before use. Never use a tire with freeze cracks, breaks, or damage to the sidewall or tread.
I found them fine at 0C in the wet, sure not as grippy as when warm, but they still lost grip quite slowly and didn't break away quickly. That was when they were new, so we'll see what happens after some use.