2006+ Honda Civic Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
47 Posts
Discussion Starter #1
had my aftermarket alloys for a while now so thought i would update you guys with my findings.

stock 2.2 idtec alloys removed and some alutecs installed. cheap rubber gone and pilot sport 4's on the alutecs.

6.5J 205/55/16 to 7.5J 225/45/17

same rolling radius but much heavier package. economy on a motorway run went from 82mpg to 65mpg. same style driving and speed.
i put on the stock wheels just to double check the mpg figures this weekend, yup its the wheels/tyres.

is it worth the mpg hit for me? most definitely, as the grip in the corners and flying starts is ridiculous (y)

i recommend getting lightweight alloys if you are in the market for new alloys. i paid £70 new per wheel for mine so obviously they were never going to be lightweight (especially with the bigger/wider size)
 

·
Registered
Joined
·
284 Posts
If it's mainly motorway, ie constant speed, then weight shouldn't really make any difference.

The main thing is rolling resistance, are the new tyres inflated high enough ?
 

·
Premium Member
Joined
·
300 Posts
different tyres have different rolling resistance - can make a big difference.

as above, lighter wheels helps with acceleration (less mass to spin) and also has improvement in ride quality but if you're at constant speed the weight is less important.

i run forged wheels with my summer tyre setup - same size as stock (18) but significantly lighter and they are "A" rated for roll. I get about a 10% improvement with those vs heavy oem wheels with cheap winter tyres..
 

·
Moderator
Joined
·
3,692 Posts
Rolling resistance aside (should only make a minor difference?) 82 down to 65mpg is plain silly. That's a 21% knock on consumption. effectively puts the price of a litre of gas up from £1.24 to £1.50
 

·
Registered
Joined
·
47 Posts
Discussion Starter #9
Rolling resistance aside (should only make a minor difference?) 82 down to 65mpg is plain silly. That's a 21% knock on consumption. effectively puts the price of a litre of gas up from £1.24 to £1.50
i agree, RR should make a difference but not by that much. the weight increase is huge though (judging by lifting one compared to OEM). what people are forgetting here is that wheel weight is 'rotational mass', acts differently to rest of the car.
 

·
Moderator
Joined
·
3,692 Posts
Regardless of rotating or static, I suspect that you would have to add quite a lot of mass to a car to knock the MPG by 20%.
But what is really causing your problem, who knows? I don't.
 

·
Registered
Joined
·
47 Posts
Discussion Starter #13
Regardless of rotating or static, I suspect that you would have to add quite a lot of mass to a car to knock the MPG by 20%.
But what is really causing your problem, who knows? I don't.
its definitely wheel related as it went back up to 82mpg with old wheels in the same weekend. the combination of increased wheel/tyre weight, wider wheel size, grippier tyres, wider track/stance is clearly combining to create such a strong effect. the mystery is the hierarchy of those changes. after some basic research, my guess would be rotational weight (3 times more pronounced then static weight when moving).

can get a better idea if someone has upgraded to 1 inch wider wheels all round (6.5j to 7.5j)
 
1 - 13 of 13 Posts
Top