My first tank on new Xb auto was right at 30. I put on 205/40-17 Potenzas on 17X7 Motegi Rojas and mileage dropped to consistent 24 to 26. I run the pressures at 35. This winter dropped to 22mpg and tires looked low so I upped the pressure to 45! that sent the mileage back up to mid 20s but still no 30s. Its warm here in Omaha now and last tank with 35 psi in tires was 25.6. My Xb is stock save for the rims and tires. I drive 80% city stop and go and I am easy on the throttle. I hate the look of the stock rims and pie tin wheel covers but 4 mpg is a big sacrifice. Any one else have a similar exp? Thanks.

 

I have 17's and get 32-33 mpg on a consistant basis driving 70-80mph. Most is freeway--but sometimes that is stop and go in LA.

 

i just put 17's on last week and my gas mileage is okay so far, around 30mpg,but most of it is highway. i hope i dont get mid 20's mpg... that would suck ..gas cost to much

 

Bigger wheels and tires create a heavier mass compared to stock.
So the engine does have to work harder to get the car moving which
would affect MPG, especially in stop and go traffic. Winter gas is
known for crappy mileage. I lost over 5 MPG during winter. Now
it's back up to normal.

 

Welcome to the club! My mpgs drop 3-4 while running my 18" TRDs. Love the look so I deal.

 

I have noticed just a slight change in mileage with my 18s, but when I bought them I made sure they were close in weight...the factory wheel/tire is approx. 40lb (I used my bathroom scale.)...my 18s are 42lb. The biggest thing I did notice was the way the wider tires track the road...kind of annoying at times, the the trade off on appearance is worth any small change in mileage to me.

 

Weight is only part of the equation.

Rotational inertia = mass x radius^2

So even if you have the exact same weight wheels, larger diameter wheels (they move the majority of the weight outwards, as almost all of the weigt is in the outer rim) will ALWAYS have worse mileage, power, and braking.

The only improvements you will see, performance wise, is the ability of adding larger brakes. Traction and handling issues can be resolved with higher quality tires (with stiffer sidewalls of the ame heigt) and wider wheels to accommodate the tires. That is, unless the new wheels are light enough to offset the change in radius (which means they have to be AT LEAST lighter than stock). Aesthetics are a different issue, however.

 

^^^ hes right, rolling resistance can be a bite in the ****. You may also want to try cleaning your MAF seonsor. I didnt notice a big loss with my summer wheels which were 215/45R17s. What little i did loose, i make up for in looks with a nice set of 17s.

 

That could be one of the differences between you and the others with larger wheels that say their mileage hasn't dropped (as much). When you accelerate, more energy goes to rotating those wheels and tires than needed for the stock ones. On the highway, you probably take a hit from increased rolling resistance and/or aerodynamics of 20 mm wider tires. I wouldn't increase the pressure- it'll make your tires wear in the middle and make your car ride rough.

You could try changing your driving habits. Maybe you'll get better mileage with heavier acceleration to get up to speed? Or a power mod or two- intake, header, etc.

 

3 to 4 miles per gallon lost...sounds about right
I'm runnin 18 thogh
but havent put them back on for the summer yet..I really like the ride quality on the stock 15's

 

your tires are the same overall size as the stock tires. your problem is not your tires. plenty of other xb owners have niticed a back and forthe jump in mpg for no clear reason.

 

ive calculated my mileage with and without the 17's on my car. The 17's threw off my odometer by 1/10th. Basically for every 1.0 mile, my car calculates .9 miles on the odometer. My major drop in gas mileage can pretty much even out if i add in all those little .1 miles that are lost. Before wheels/tires i was gettint 300-320 a tank After wheels and tires im getting 260-280 a tank.


take .1x280=28

280+28=308

Putting me back on track for my old average with stock tires.

 

That's why lots of people are going back to 15" aftermarket wheels. I like my 18"s too much to worry about those 3-4 mpg tho.

 

you must have 17's made of lead....

 

i had 15" allows for a while , no change in milage, im a VERY conservative driver though, i switched last year to 17" x 7" and i would swear they almost felt lighter then my 15's , either way i avagerage between 32-38mpg depending on whether i drive around town or back and forth to la.

 

I really like how mine looks with the 18's..but I got an issue I got a stripped wheel stud I need to replace before I can put the 18's back on.I was even considering putting new longer wheel studs all around ,so there would be enough threads for the wheel lugs to bite onto

ahh..but the ride quality with the stock 15's...hmmm I guess vanity has a price

 

yeah since changing up to 17" with the 35 profile its been a big change , have to be carefull of pot holes , the ride does get a lot rougher but i got more control and much better stopping response too. new wheel lugs are cheap and i hear their really easy to install ( oh yeah 18's are a hella pricey when they get busted my bf has VW 18s and had to replace a busted wheel and tired cost him $ 750.00 )

 

ride quality you call it? ha ha you guys mean squishy non connected road feel , body roll due to the baloon tires? ha ha

 

If you swap out the stock tires with 195/60/15 tires, there are plent of high performance uptipbs available that will get rid of the squishy balloon feeling. The stock ride quality has more to do with crappy tires than the larger sidewall. Those tires were NOT designed for performance. Besides the import scene, no professional racing cars use rubber band tires. Just look at F1. Their huge sidewalls make our stock 65 series look like low profile tires!

It's best to compare apples to apples, and comparing OEM wheels and tires to wider aftermarket wheels with sport tires is not a fair comparison.

 

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