Anyone lose MPG after switching tires or wheels?

[Gawernator]

I went from the OEM 16" wheels and tires to 18"x8 DRAG wheels which are heavier and wider, and a Michelin MXM4 primacy tire. It seems like I'm down about 1.5-2.5 MPG overall on the freeway or overall total. Hard to say since there's a lot of other variables. But I used to see 32-33 mpg on the extended counter and now it's about 30.5. Anyone else have similar results? I used to get low 40's MPG freeway. Now I get about 38-42 it seems.

https://imgur.com/a/xmNqX

 

[Fanis1]

Seems pretty normal to me. Wider, stickier tyres along with greater mass equals worse gas mileage

 

[kinch]

The circumference of your new wheels is greater so your car is doing more miles than what it thinks. Your mpgs should be the same if you do a brim to brim calculation.

 

[Gawernator]

The circumference of your new wheels is greater so your car is doing more miles than what it thinks. Your mpgs should be the same if you do a brim to brim calculation.

Hmm that's a good point. How can I re program the car? 17-19" wheels are all options on the Golf series.

 

[Gawernator]

Seems pretty normal to me. Wider, stickier tyres along with greater mass equals worse gas mileage

Yeah it would make sense. Just wondering what people with larger wheels factory are getting.

 

[JC_451]

If you didn't calibrate the speedometer the car doesn't know how fast you're actually going either.

 

[Derushi]

Yeah it would make sense. Just wondering what people with larger wheels factory are getting.

19" here. I normally get between 28-32mpg in a 15-20 mile commute half city/hwy, 65-70mph hwy cruise.

I think when I had the 18" I get low to mid 30's mpg in the same commute.

 

[Jargy]

I think the total wheel and tyre width would still be similar - bigger alloys usually just mean thinner rubber, so the speedometer would be fine. The greater tyre road contact would impact on your mpg though.
I may be wrong.

 

[golfdave]

The circumference of your new wheels is greater so your car is doing more miles than what it thinks. Your mpgs should be the same if you do a brim to brim calculation.

If you didn't calibrate the speedometer the car doesn't know how fast you're actually going either.

IF the OP sticks to the accepted lower tyre profile sizes then the outside rolling circumference of the tyre can be the same whilst the alloy wheel increases in diameter...less side wall ..

Please learn basic wheel tyre & alloy information, plenty on the web.


To The OP the main reason is the increase in aero drag of the tyres which are wider....ECO cars have narrow tyres for a reason....you did the opposite increase air resistance & friction/drag..

You can get very lost in complexities of the increased footprint of the car via the tyres but the car remains the same weight, but wider tyres , but less weight of car per square inch of tyre contact area as more contact area... etc.etc.

 

[JC_451]

^
Sorry, I assumed the circumference would be different.

You did say IF. No need to be mean about it

 

[Gawernator]

I feel some remorse because the wheels I got are supposedly 23 lbs each (I got them dirt cheap new through my cousins shop) because the Konig I wanted were on a 2+ month backorder. Not sure about OEM wheel weight but surely it's less... similar wheels for more money seem to be around 17.5-21 lbs. so I'm not sure how noticeable the weight difference is in daily driving. Certainly not good for acceleration however the wider tire patch has greatly reduced my wheelspin

 

[Gawernator]

If you didn't calibrate the speedometer the car doesn't know how fast you're actually going either.

Any guides on how to redo this? Also my tire size/profile is now 235/40/18. The overall sidewall size does seem to be a little thinner but definitely not rubber band size or anything.

Pics of car https://imgur.com/a/xmNqX

 

[JC_451]

According to the others D) you likely do not need to calibrate the speedo.

 

[Gawernator]

If you didn't calibrate the speedometer the car doesn't know how fast you're actually going either.

The car says 65 MPH and my GPS also says 65 mph. Flawless!

 

[JC_451]

Yeah just ignore me being dumb. Assuming facts not in evidence (larger overall circumference of the wheel/tire)