No MPG Winner - but I'm happy

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03BeigeGolfTDI

Well-known member
Joined
Sep 23, 2003
Location
Massachusetts
TDI
03 Mojave Beige Golf TDI GL
No MPG Winner - but I\'m happy

as the name says 03 Golf GL (4 door) TDI
~34k miles
swapped out 15" steelies w/ GY's to 16" BBS RXIIs on brand new Conti's.
MPG went from 44 to 49...almost all highway. i'm a little confused about the MPG going UP but i can't complain. everything i read said "bigger wheel, lower mpg"...

will i see the same result changing to the .205 injectors too???
 
G

GetMore

Veteran Member
Joined
Apr 10, 2003
Location
Patterson, New York
TDI
1997 Passat TDI, 2010 Jetta Sportwagen
Re: No MPG Winner - but I\'m happy

That probably explains it: lower rolling resistance due to proper inflation. Tire pressure makes a big difference.
Though one day I would like to see a comprehensive test on rim size and its effect on mileage. It'd be nice to see if going wider is the culprit, if it really is diameter, or if it's the tire itself.
 
jnecr

jnecr

Veteran Member
Joined
Oct 9, 2004
Location
Raleigh, NC
TDI
2014 BMW 328d
Re: No MPG Winner - but I\'m happy

It'd be nice to see if going wider is the culprit, if it really is diameter, or if it's the tire itself.
Click to expand...
All of the above, plus the weight distribution of the wheel/tire.
 
E

Ernie Rogers

Veteran Member
Joined
Oct 15, 2001
Location
Pleasant Grove, Utah
TDI
Beetle, 2003, silver
Re: No MPG Winner - but I\'m happy

With bigger tires, the odometer shows less miles traveled for the amount of gas. Further, IF you are careful enough to try to drive the same speed as before, the larger tires will fake you into driving faster than before. Overall consequence is that you might suppose (without making the necessary gage corrections) that fuel economy IS GOING DOWN with bigger tires, when in reality your mileage would increase (in agreement with theory). This was covered in detail in another thread.

Ernie Rogers

Were I to guess, your calculated mpg went up because your odometer is wrong as a result of the larger diameter tires.

http://www.miata.net/garage/tirecalc.html
Click to expand...
 
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