I got my MINI out for its first real drive of the year. I diid 400 miles and averaged 37.8 mpg. Everything was great, but I really am getting tired of the run-flat tires(Continential all seasons 205/45-17). I'm planning on switching to non run-flats, but I'm a little worried that I might see a drop in gas mileage. Has anyone noticed a drop in mileage after changing to standard tires?

 

It may depend on what you replace them with. I see no difference with the Continental DWS I went to (I'm on my second set 215/45-17). However, the Michelin winter tires dropped the mileage about 10%. I had a similar experience on my Miata... going to GY Eagle F1 A/S dropped the mileage almost 10%, but the new Eagle GT A/S was very close to the original tires in terms of fuel economy.

 

In addition to the comfort/handling improvements, even if you lost 3mpg from 37.8mpg and you drove 30k on $4 gal gas, it will only cost about $300 more per year (or set if you get 30k life on the tires). Still cheaper than replacing with runflats.

 

If you go with wider tires, there may likely be a drop in mpg due to increased friction.

 

choice of tires, (brand and type (summer, A/S, etc.)), their weight, whether sold as fuel saving type explicitly, inflation pressure etc. And yes a totally inflexible brick might indeed win on mileage, but it's not practical.

As another poster mentioned, also factor in the cost of the tires. Four top line Michelin PS2's cost me over $500 less than the Dunlop RF's on mine even via TireRack. Lots of decent tires out there that could pull out even hundreds more.

Net, that's a lot of gas! And, my mileage seems the same basically for the record pre- and post tire change. 25-26 based on real measurement (not the optimistic computer), heavily around town rather than highway and w/ spirited driving (including teens), on a 2010 S coupe w/ 6 speed. In my case I went from 205's to 225's as well, but was careful to not increase net tire weight among the choices I had.

 

Get low rolling resistance rated tires. The Michelins in my sig netted 3MPG more over the OE Conti runflats.........

$70 Michelin rebate going on now to boot........