A quick perusal of the BMW F10 (5-series) forums will show many (most) owners with 19" rims (standard on 535/550 M-Sport models) have had problems with blistering tires and bent rims. The tires are the same 245/40-19s on the Q50 sport. Even the same tire, the rather antique Bridgestone RE50A RFT with a wear rating of 140 (one-four-zero).
Owners with 18" rims (245/45-18 tires reported no problems. Owners who changed to non-runflat tires (usually Michelin Pilot Super Sports) reported no or few problems.
I note that Infiniti has a spare tire on the options list. One problem the BMW owners have is that once you drive on a flat runflat it has to be replaced. The cost of a RE050A RFT in 245/40-19 is around $400. For comparison a Michelin PSS is $275 and a Bridgestone S04 is $201.
Additionally, as a quick look at Tire Rack will show, all the tires available in that size are pretty old designs. The best/newest may be the all-season Bridgestone RE960AS Pole Position RFT. However, by the time that tire was introduced, the non-runflat version was already replaced with the RE970AS!
Are people here expecting problems, planning to replace the tires with non-runflats, or keeping their fingers crossed?
Owners with 18" rims (245/45-18 tires reported no problems. Owners who changed to non-runflat tires (usually Michelin Pilot Super Sports) reported no or few problems.
I note that Infiniti has a spare tire on the options list. One problem the BMW owners have is that once you drive on a flat runflat it has to be replaced. The cost of a RE050A RFT in 245/40-19 is around $400. For comparison a Michelin PSS is $275 and a Bridgestone S04 is $201.
Additionally, as a quick look at Tire Rack will show, all the tires available in that size are pretty old designs. The best/newest may be the all-season Bridgestone RE960AS Pole Position RFT. However, by the time that tire was introduced, the non-runflat version was already replaced with the RE970AS!
Are people here expecting problems, planning to replace the tires with non-runflats, or keeping their fingers crossed?