Mercedes GP have made no secret of their issues of managing the rear tyres, and they have moved to resolve that issue through some aerodynamic tweaks. Since Turkey, the W02 had a small turning vane fitted on top of the car's floor, just ahead of the rear wheel. This element tries to keep exhaust gases away from the tyre's frontal surface and instead guide them onto the diffuser.
Other teams are having much less issues here because most, including Red Bull and its copycats, channel the exhaust gases in a double floor right onto the diffuser, instead of exiting from the sidepods in open air. Renault on the other hand, having front exit exhausts indirectly heat their rear tyres as well with the exhaust gases, but they are currently very happy with the car's easiness on the Pirellis.