I bought a used 09 xB the other day. I am looking into new rims/tires.

The purpose of buying this car is for fuel economy. Is there a difference in MPG from stock setup to 18" wheels/tires?

Thanks.

 

It's all about weight. If you get 18's that are the same or lighter weight than the steelies, and go with light weight tires in the 215/40 or 225/40 size range you'll be fine.

 

Thanks. Is there anyway to re-calibrate my speedo for the bigger wheels?

 

You don't need to. Accuracy of the speedo/odo is based on the outside diameter of the tires, and has nothing to do with wheel size.
OEM 205/55-16 tires calculate to 24.9" diameter.
215/40-18 = 24.8" diameter.
225/40-18 = 25.1" diameter.

To see the effect of different wheel & tire sizes versus OEM, use this calculator:
http://www.rimsntires.com/specs.jsp

Keep in mind that the stock wheels are 16"x6.5" with +45 offset, and the tires are 205/55x16". Have fun playing with the calculator/comparer.

 

Thanks for the help!

 

Lost a bit with my 19's(-1.8mpg), but I'll stick with them cause they look so sweet!

 

read for yourself.

http://www.caranddriver.com/features...sted-tech_dept

 

For fuel economy the best wheels/tires would be the oem 16" alloys with oem size tires. In addition to the extra weight with larger wheels, wider tires also hurt fuel economy by increasing rolling resistance and aerodynamic drag.

 

So can someone supply the weight of one OEM wheel + tire + wheel cover, please.

 

As close as I can tell an oem 16" steelie weighs 21-22lbs + 20lbs for the oem Goodyear tire. The oem 16" alloy weighs ~18lbs. I have a set of oem 16" alloys with oem Goodyears in my basement and they weigh ~37lbs each on a very questionable bathroom scale. Best I can offer...

 

For what it's worth, with TRD 19s, my city/hiway commute brought me in around 24mpg. CAI and TRD Exhaust. My friend with factory wheels gets about 2mpg higher on average.