Crosswind and Tailwind: Relative limits
 

Are there any aircraft where the max certified tailwind is higher than max certified crosswind limit for landing performance? Or is this a fundamental impossibility of design.

For most jet transport aircraft, you're looking at the region of 30-40kts maximum demonstrated crosswind and 10kts for a tailwind. Specific figures depend on type.

I'm not aware of any aircraft that have a tailwind limit higher than the crosswind limit.

Not sure whether it's impossible to design an aircraft like that, but it's fairly pointless because you need a higher crosswind limit because you can't turn the runway into wind. You don't (usually) need a high tailwind component because you can use the runway in its other orientation and fly with the headwind.

For those airfields that have preferential runways, their corresponding notes in the Jeppeson plates usually say that the runway will be used up to and including a 10kt tailwind, before the non-preferential is used.