bigger tires = bad fuel consumtion?

[tesna]

Hi all,

I got a question, I recently put 18" enkei wheels on my V6-24 Auto with 225/45/18 rubber on it. But lately eversince I put those wheels on my car my fuel consumption increased significantly. My standard rims are 15" with 195/60/15. I already got wheel alignment done. The diameter difference is about 7% larger than my standard wheels. Is that enough to add 10-15% increase in fuel consumption? should I swap the tires with 225/40/18 ? or is it the fuel consumtion increase is caused by other factor?

I also was using 19" rims with 225/35/19 tires on it, but the fuel consumtion much less the same as using 15" rims. I swap to 18" due to ridiculus price of 19" tires, and the rims were bent.

Or is it because bad fuel? I always use 95 RON unleaded (the highest RON available in my country) on my car.

Thanks,


Tesna

[mpau009]

I think you might be correct, i know that large rims, chrome in particular can have a lot more inertia, meaning its gonna take more force to accelerate, brake and turn. I know on other cars that my friends have, the braking and handling turns to **** when they upped the wheel sizes. And that bearings and suspension parts can take a hammering. I guess if you need to push the go pedal that little bit more to get up to speed, then you are going to use more gas.

Be interested to see what other people have to say.

[tesna]

mine isn't chome, in fact it's lighter than my 19" k-speed rims. My 19" was about 10kg each, and this one about 7-8kg (without rubber). Overall diameter is larger though, when using 225/35/19 the diameter difference from standard rims only about 5%, whereas using 225/45/18 the diameter difference increased to 7%. If I change to 225/40/18 tires, the diameter difference will be only about 3%.

I did notice minor degrading in acceleration and braking performance, but nothing major I think.

[Gly]

what he said ^^

i would check you EGO sensor?
could have died suddenly, causing you car to run rich??

[bradc]

Yeah you'll definately get worse acceleration and fuel economy with bigger tyres, if you really have to have 18's then go with 225/40/18

[n13l pm]

Someone please post a picture of their galant on 19"s which is also lowered aswell.

Thanks in advance

[tesna]

what he said ^^

i would check you EGO sensor?
could have died suddenly, causing you car to run rich??

Sorry I'm a noob, what's EGO sensor? how do I check it?

Btw, today I go to exhaust shop to check on my exhaust.. and they detect a little leak!! so I ask them to fix it. They said about the joint not having good connection or something, maybe when ask someone to put my standard muffler back after I decide to ditch my HKS rear muffler. It was so damn noisy... Let's hope fixing the leak can bring improvement on the fuel ecomomy.

Thanks for your response everyone :) I'm really appreciate it.

n13l pm, here's the picture of my galant when using 19"
http://img226.imageshack.us/img226/9885/galant11jw.jpg
http://img293.imageshack.us/img293/4893/galant25fp.jpg
http://img210.imageshack.us/img210/5214/galant32sz.jpg

EDIT: fix broken link on pics.

[Funkstar]

http://img226.imageshack.us/img226/9885/galant11jw.jpg
http://img293.imageshack.us/img293/4893/galant25fp.jpg
http://img210.imageshack.us/img210/5214/galant32sz.jpg

EDIT: fix broken link on pics.

Drool......drool......drool :o /JawDroppi

[Gly]

Sorry I'm a noob, what's EGO sensor? how do I check it?



exhaust gas oxygen sensor...
looks like a bolt with a wire coming out the top...

it sits a little in front of the cat-converter..
on the right side of the exhaust angled up towards the floor of the car....


you will need to find the plug of this in the car..
it will found when you remove the passenger side kick panel next to the stereo,

i think its the blue wire that needs to be connected to a volt meter, other lead to ground....

while driving the voltage should fluctuate up and down rapidly....

i cant remember the exact voltages...

but if its changing slowly or not at all then its stuffed.

[tesna]

exhaust gas oxygen sensor...
looks like a bolt with a wire coming out the top...

it sits a little in front of the cat-converter..
on the right side of the exhaust angled up towards the floor of the car....


you will need to find the plug of this in the car..
it will found when you remove the passenger side kick panel next to the stereo,

i think its the blue wire that needs to be connected to a volt meter, other lead to ground....

while driving the voltage should fluctuate up and down rapidly....

i cant remember the exact voltages...

but if its changing slowly or not at all then its stuffed.

ok, thanks for your reply. But what if my car doesn't have that sensor? Yesterday when I put my car in the exhaust shop I'm also take a look on the undercarriage of my car from the front to back. And I think I didn't found any sensors or cables on the exhaust. I even didn't found CAT converter in my car. I think all galant sold in my country doesnt have CAT converter installed from factory.

[Gly]

it should have both from factory...

unless its been modified....

ill get a pick for you tomorrow

[n13l pm]

^tesna's pics, Wow the 19s looks Heavy mate. What have you lowered your car by and with what springs or/and shocks? Do the tyre rubber inside the arches at all?

[caishanvr4]

Car looks nice on those 19's tesna /notworthy

[tesna]

Thanks for the compliment guys, I do really like my car when using 19" tires, but after seeing the current prices of 19" tires and the rims were bent, I choose to downgrade to 18". I'm using koni adjustable shocks and h&r springs. No tire rubbing at all, I got the fenders rolled though.

Gly, today I snapped picture of my undercarriage when doing wheel alignment after I replace the ball joints and front lower arms. I hope this one clear enough, sorry for crappy mobile phone camera :P. I think there is no cat converters there.

http://img381.imageshack.us/img381/1696/photo0178bg3.jpg

In the process of doing the wheel alignment, they found out that one of my tires a lil bit underinflated, maybe that's causing bad fuel consumption. All other 3 tires got 35psi, whereas one of them only got 28 psi.

[Gly]

ok thats different to mine... you have a front wheel drive where as mine is 4WD...

you may have one EGO per set of 3 cylindrs..
so they may be higher up connected to the manifolds.

[Wodjno]

Hi all,

I got a question, I recently put 18" enkei wheels on my V6-24 Auto with 225/45/18 rubber on it. But lately eversince I put those wheels on my car my fuel consumption increased significantly. My standard rims are 15" with 195/60/15. I already got wheel alignment done. The diameter difference is about 7% larger than my standard wheels. Is that enough to add 10-15% increase in fuel consumption? should I swap the tires with 225/40/18 ? or is it the fuel consumtion increase is caused by other factor?

I also was using 19" rims with 225/35/19 tires on it, but the fuel consumtion much less the same as using 15" rims. I swap to 18" due to ridiculus price of 19" tires, and the rims were bent.

Or is it because bad fuel? I always use 95 RON unleaded (the highest RON available in my country) on my car.

Thanks,


Tesna


Answer Yes /Elmo Sort of :laugh:

Reason being is that your Odometer is reading 7% less miles for starters ? So if you go 400km your odometer will only read 372km. So it looks like you are actually getting less MPG where you are in fact achieving the same :smash:

That said though.. Your MPG will increase slightly due to the fact there will be a greater rolling resistance on the larger circumferene wheel !! What % exactly i don't know, but it will incraese !

I would say that your overall increased MPG is probably only 3-5%, not the 10 to 15% you first thought.. /Hmmm

The correct tyre size for your 18's are 225/35/18's !!

[tesna]

wodjno: Yeah, I'm agree with you. Thanks for your response. As for 225/35/18, I think the rubber will be to thin, will not looks good hehehe.

As for fuel consumption, let's hope that after I fix several things (exhaust leak, and lil bit underinflated tires) It will improve my fuel economy. Now my car feels bit more responsive.