Anyone have a caclulator for fuel economy after changing wheels?
 

I've got a car with 19" and 20" wheels front and back, and they are relatively heavy. The stock size is 17". Just how much of a hit on fuel economy could that be?

Is there any calculator to measure this? I can weigh the wheels and tires to get a more accurate figure.

Ideas?

There is no *accurate* calculator for it because there are too many factors that affect your fuel economy, even if you only change the wheels.

If you do more highway driving, larger wheels can actually marginally improve your fuel efficiency. In the city it will hurt you, depending on how hard you accelerate from stops.

The rolling resistance coefficient of the tires and the contact patch size will also have an affect on fuel economy.

Your alignment will also make a difference too.

I switch from 16" 11lbs wheels to 17" 28lbs wheels and the difference in fuel economy was nil, however you could feel the steering was much heavier.

The answer you may not be looking for, but the cold hard truth, is that your driving style has a wayyy bigger affect on fuel economy than wheels will.

fill your car up full, reset your trip A odo (or b w/e u want).
Write down how many KM you got out of your tank
figure out how big your tank is
do the math
profit??? :lol

so much work! but thats the most accurate way lol

this is the only true way...........

I calculated mine awhile ago, heres the math i did
Put in $100x$1.49 for 91
=67.11 L
67.11 L = 408km
408km Divide 67.11 L=6.08km/L
6.08km/L x 3.78 (3.78L to a Gallon)
6.08km/L x 3.78
=22.3 MPG Highway

the proper way would be to include the Miles in MPG. you did KmPG.

your car is really 13.93 mpg



My Evo which is over 500hp is :

250miles / tank

13.2 gallon tank

18.93 mpg

50L x 1.49 = $74.50

$74.50 = 400kms (250miles)

1. fill tank completely
2. reset trip meter to zero
3. drive normally until you want to refill the tank
4. record how many km you traveled on the receipt
5. the receipt will tell you how many litres of gas you refueled with
6. calculate your L/100km by solving for x

_x L_ = amount refilled(L)
100km distance traveled(km)

7. you can convert to MPG if you wish

A better way is an average over 3 or more fill-ups to take away random errors.

Never thought of it doing it that way..