mpg's and aftermarket rims???

[only1db]

ok...i have been driving like 90 miles one way to work lately. i found some used tires (too cheap to buy tires) 215/45 r 17's i know that they are slightly oversized. but i put them on my 17's and drove for a week. i went from 32mpgs and 400mpt to 28 and down to 350mpt. i'm no[t sure if its because my rims are slightly bent (ever so slight wobble) i roadforced balanced them and the numbers are all under 15.

what is everybody else getting with their rims??

please denote tire size and average mpg's


i'm considering going down to a 16 (it will still clear the tib brake upgrade i have planned)

any help would be appreciative.

[Tommy]

bent wheels wont do it, but you have to factor higher rolling resistance of the tires and heavier wheels will make a substantial difference.

i took about a 10% hit when i went from the factory alloys to what i have now.

[cbogg]

Has anyone ever given any thought to rims and PERCEIVED mileage? If you go with an undersize tire, you'll be traveling the same distance, but showing MORE mileage because of the smaller tire, hence a "gain" in MPG. An oversize tire would show LESS miles as you're traveling the same distance, with less tire rotations, but the same reading on your odo. Maybe your mileage stayed the same, but it just appears that you lost?

[Tommy]

well, what he has is only 1.8% difference over stock.

he's taking a 12.5% loss since the new tires. So its not all tire size.


Maybe obvious, but since you had the new tires, what tire pressure are you running? I know everytime i end up at a shop for something and the check the pressure, they drop it down to like 28psi, which is bs. i run like 38-40psi

[cbogg]

It was just a thought....

[only1db]

the assy weights less then the oem rim and tire.

perhaps a 215/40 would be a better choice

[BobMs_wht2k2]

The wider tires are what's killing you the most. My 225/45's get less mileage than the 205/55R16's that are oversized. Likely due to the wider tire and the stickier compound. Drop to a 205/45 if mileage is all you are looking for and be sure it's an all season with high treadwear.

225/45/16's on 15lb Konigs and I get BEST of 34mpg.
205/55/16's on 24lb Sonata wheels and I get an average of 35, best of 38.

[kylemorg]

the assy weights less then the oem rim and tire.

It's not simply the overall weight, but where the weight is in relation to the hub which effects the inertia of the wheel and tire.

With a bigger rim, you're pushing most of the weight of the rim and tire towards the outside of the circle, which increases the inertia of the system. That makes the wheels take more power to spin up and more braking force to slow them down (even if they weren't in contact with the road surface).

You will loose some mpg running bigger wheels, unless the center of inertia (not the center of mass which is at the hub) is in the same place as the stock rims.

[i8acobra]

Your best mileage would be with a 15" alloy wheel with OEM sized tires. The lighter, the better. Every "plus" size you go up is going to reduce your mileage a little due to the added weight. Weight and width are going to effect your mileage.

[only1db]

thats why i was thinking 16's enough sidewall that i wont bend my rims again, but low enough to give me some response in the corners (down here that would off/on ramps) but still look better then that damn balloon tire.

thanks for the input...

keep them coming...more the merrier

[i8acobra]

A 205/50-16 will be almost identical in height to your stock 195/60-15's. That's what I'd recommend.

[BobMs_wht2k2]

Correct, unless you do a ton of highspeed highway driving. Then a 205/55 allows a little better top end gearing to lower engine rom's. Downside is the need to remember that 75 is not 75, but closer to 77/78.

[Cypher]

The wider tires are what's killing you the most. My 225/45's get less mileage than the 205/55R16's that are oversized. Likely due to the wider tire and the stickier compound. Drop to a 205/45 if mileage is all you are looking for and be sure it's an all season with high treadwear.

225/45/16's on 15lb Konigs and I get BEST of 34mpg.
205/55/16's on 24lb Sonata wheels and I get an average of 35, best of 38.

My 225/50r15s are getting me 37-38mpg. I guess once I throw on the steelies with oem sized tires I might be able to break 40.

[BobMs_wht2k2]

But are your 225's treadwear rated at 180/200?

[Cypher]

340, I didn't say they were super grippy ;) They are all seasons.

[BobMs_wht2k2]

Add wide tires PLUS grippy compound and you WILL lose MPG.

[Cypher]

I wasn't arguging with you, just stating that my all seasons in a 225 width are doing fine for me.

[SilverElantra]

The wider tires are what's killing you the most. My 225/45's get less mileage than the 205/55R16's that are oversized. Likely due to the wider tire and the stickier compound. Drop to a 205/45 if mileage is all you are looking for and be sure it's an all season with high treadwear.

225/45/16's on 15lb Konigs and I get BEST of 34mpg.
205/55/16's on 24lb Sonata wheels and I get an average of 35, best of 38.

hmm wonder if thats another factor in why my MPG's are so low. i have a 7 inch wide rim. 205/40 17 that are nitto neogen's and they are sticky as hell, cant even get them to burn out from a 2500-3000 rev(brake stand)

[BobMs_wht2k2]

Wide rims mean nothing with skinny tires. Your problem is the gross undersizing of your tires.

[SilverElantra]

makes my mpg's go down?

[kylemorg]

Wide rims mean nothing with skinny tires...

Except for the added inertia (spinning) mass, which if you accelerate or decelerate frequently will make you loose a bit of mileage. The same design and diameter rim in a 5.5 section width will weigh a bit less than one with a 6.5 section width and have less inertia, which yields slightly better MPG.

[cbogg]

yeah, because the circumference is less, it takes more revolutions of the tire to go the same distance, hence the motor is spinning more to travel the same amount which means your gas mileage is going down as you're using more fuel to travel the same distance.

[BobMs_wht2k2]

yes. You push your final drive up, meaning you have to go "faster" to keep up with traffic.

Fo instance, your tires are 4-5% off. So when your speedo show's 50, you'rereally only doing 47/48. At 70 you're only doing 66/67. To actually GO 70 you have to go 74. so your car is burning the gas it would take to run 74mph, to physically go 70.

Considering anything over 3200rpm's in the 01-03 non-cvvt enters into horrible fuel maps, running the car at 78mpg indicated going 73/74 puts you into "OMG, gas mileage sucks balls" range.

Going slightly oversized does the opposite at highway speeds. At an indicated 70, you're really going 74. So the car goes faster than it thinks, allowing the engine to run at slower rpm's.

Yes, an undersized tire will help initial acceleration because it's changing the final drive, but it also hurts mileage by spinning the engine too fast.

Except for the added inertia (spinning) mass, which if you accelerate or decelerate frequently will make you loose a bit of mileage. The same design and diameter rim in a 5.5 section width will weigh a bit less than one with a 6.5 section width and have less inertia, which yields slightly better MPG.

True. One needs to take into consideration their driving habits and style when choosing a wheel/tire combo to suit their needs. I need something for a lot of highway cruising and little to none stop-n-go. That's the reason my "DD" tires are taller than stock.

[SilverElantra]

since i have opted to keep these rims, and am going to be lowered on HR's what would you recommend then as the "best" sized tire?

[cbogg]

205/45 17's. Bryan (bidggy) rubs with 215's and h&r's, I rub lowered more on 215s (but only in the front for some reason, go figure that one out). 205/45 is your best bet not to rub, and keep your speedo and mileage as close to stock as possible.

[BobMs_wht2k2]

^ As long as your offset is close. Keeping the offset between 42-46 is ideal. 40 can be done with a little more negative camber.

[SilverElantra]

i plan to do an aggressive suspension set-up as i like to drive the "canyons" so i might be able to get away with 215's. i also have 5mm spacers all the way around.

[BobMs_wht2k2]

Spacers are going to be a problem. Most wheels are too shallow to start with, pushing the tires outwards. We RARELY have a problem of tires rubbing the suspension. Take the spacers off, you don't need them.

[SilverElantra]

actually Bobbo i do need them if you recall any of my other threads my rims do not fit properly unless i have the spacers on. Has been covered too many times and do not wanna go over it again.

[cbogg]

I couldn't find the offset on your rims in a post somewhere, but I'm tellin ya there ain't gonna be **** for room with 215's and 7" rims, and depending on your current offset, that might push it out too far for 215's, I can't explain the math, but it works in my head.

[SilverElantra]

i dont know the offset of my wheels to be honest with ya.

[cbogg]

Yeah, but I do think you're gonna rub with anything bigger than a 205. Even if those were 45 offset rims, you'd still be dropping down to a 40 offset (basically), and rub.

[SilverElantra]

so a 205/45 will fit, but i could not push a 50?

[cbogg]

a 50 series on a 17 is too tall. 45 gets you closest to the stock tire height and circumference. You could probably put them on, but it might hit the fender liner, and bring you closer to the infamous rubbin bolt.

[SilverElantra]

i plan on getting my fenders rolled and pulled later on down the road, but i do not want rubbing issues till then.

[cbogg]

It's either gonna be, roll now, and have no issues later. Get narrower tires now, roll later, and have no issues, probably another wider set after that. Or the alternative, drop it, roll later, and have issues now.

[SilverElantra]

o well

[Cypher]

Do it once and do it right.

[cbogg]

exactly

[SilverElantra]

its expensive to have fenders rolled and pulled(correctly) i going for the KDM pulled look. im waiting till i get my body work done, which nothing really is getting done to the car except the tibby sway bar and possibly front strut bar, till the car is paid off, which really isn't that long, but still cost grit to do the fenders.