//// Will 2" lift hurt aero ? ////

[JSH]

The 2 inch lift on my Astro van didn't effect mileage in a measurable way - 17.0 mpg average the year before and 17.1 mpg the year after the lift.

Going from stock 215/70R16 tires on 16 x 6.5 wheels to 235/65R16 tires on 16x8 inch wheels dropped my highway mileage about 1 mpg. They are heavier, with 3/4 inch more tread width, and 1.9" larger in diameter. The wider wheels and different offset increased track front and rear by 4.45 inches. The better tires and increased track completely transformed the ride and handling. Much more stable in curves today with less body roll. The lift means I can do high-clearance forest roads without worry of bottoming out. (I dented the oil pan on my 2003 Jetta TDI)

EDIT: 1 mpg was 6%

[bobo333]

Changing the wheels and tyres on my Prius had a big negative impact on mileage, some of which i can attribute to the increased weight (i havnt actually weighed them but the new ones are much heavier) also the different tread and compound (Toyo All Terrains vs factory LRR Prius tyres) and the larger diameter changing the gearing enough to affect acceleration (the big tyres need much more torque to get moving). Finally theres the height increase which means more frontal area and therefore worse aero.

My new combo is 215/70R16 vs the factory Prius 185/65R15, the mileage now is around 6L/100km vs 5L/100km beforehand

[JSH]

I've also seen pretty large decreases in fuel economy from wheel and tire upgrades

2003 VW Jetta Wagon TDI: 195/65R15 to 205/55R16 was a 6% drop in fuel economy
2005 Toyota Prius: 185/65R15 to 205/55R16 was a 7% drop
2009 Toyota Prius: 185/65R15 to 195/65R15 was a 6 % drop
2016 Spark EV: 185/55R15 to 195/55R15 was a 7% drop.

All of those were an upgrade in compound to. The all-seasons that come stock on most cars are generally pretty bad. I like to upgrade to a performance all-season with good wet weather performance.

[SkauneJohan]

in a few months I will have an answer to that

my car was lowered and scraping everywhere(bad roads here) and so I changed springs to standard wich is significantly higher, will measure how much higher later when i got time

[cRiPpLe_rOoStEr]

Originally Posted by bobo333

the larger diameter changing the gearing enough to affect acceleration (the big tyres need much more torque to get moving)

That was a matter of concern for me when a friend asked me to do the math to find out if it would be worth to try slightly taller tyres in his truck. But since he didn't overload it and AFAIK didn't use its entire payload capacity, it served right for him. Width remained the same though.