Bigger wheels vs mpg - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

v6_camaro · 04-04-2013, 02:14 PM

I'm thinking of upgrading my 18" to 19" or 20", how much mpg am I gonna lose?
I'm consistently getting 20.5 mpg right now with standard 18"

Angrybird 12 · 04-04-2013, 02:26 PM

Well you need to keep the rolling diameter the same to keep from changing your MPG. If you change rolling diameter of the tire/wheel combo you need to have the computer program changed to compensate on your MPH and Odo readings. Larger wheels and tires should actually increase your mpg because your gearing remains the same but it takes fewer revolutions per mile of the driveline. Your acceleration will suffer though.

That being said if you stick to the stock GM tire sizes for the different size wheels you should not have to compensate and it should not effect your mileage.

Wilson_51 · 04-04-2013, 02:44 PM

I have 22's on front and 24's on back and havent really noticed any change in MPG. Now my speedomoter was off 5, but i used my programmer and fixed that.

OmniCamaro · 04-04-2013, 02:48 PM

Your DIC will show worse gas mileage. How do I know? I put smaller tires on my rears(low profile) and my MPG went up quite a bit. You'll have to tune your gear ratio to fix it after changing. PM me if you need help.

Also remember that the front tire diameter and the rear tire diameter have to be within a certain tolerance(sorry,I forget the number now) or your nannies will go nuts on you when you start driving.

v6_camaro · 04-05-2013, 01:24 PM

I'm leaning toward 19" with 45 profile, would I get a slightly better mileage since the overall diameter is smaller than the stock 18"

ka1 · 04-05-2013, 03:54 PM

Quote:

Originally Posted by v6_camaro

I'm leaning toward 19" with 45 profile, would I get a slightly better mileage since the overall diameter is smaller than the stock 18"

19" wheels/tires are sometimes hard to locate at a decent price in my experiences. Might be better going 20s

intensifi · 04-05-2013, 04:23 PM

more weight = less mileage

An article on the new Z/28 in Consumer Reports stated the 19" inch wheels/tires weigh less than the 20" wheel/tires on the SS & ZL1 ( & RS )

http://news.consumerreports.org/cars...power-war.html

I think what this means is if you could find a 19" or 20" wheel/tire combo that weigh the same as your 18"s there would be no difference.

Fish-man · 04-05-2013, 04:49 PM

Tires have several things that will affect mpg.
1-rolling resistance
2-width
3- Overall diameter
4-"weight"

1 is probably the most influential, but is also the one you wont find out unless you have a dyno that measures rolling resistance. Generally, moving from a all season tire to a summer performance tire will make for higher rolling resistance

2 if the tire gets wider, it makes the car have more frontal area... and therfore more drag

3 if the tire gets taller, it raises the car off the ground, and allows more air under the car, making mpg worse

And a fourth, mass (rather rotational inertia), is probably harder to quantify, since the portion of driving that is stopping and starting is relativley small. Something that you can feel in accel/braking though.

04-04-2013, 02:14 PM	#1
v6_camaro Drives: 2013 Camaro 1LS Join Date: Sep 2012 Location: California Posts: 31	Bigger wheels vs mpg I'm thinking of upgrading my 18" to 19" or 20", how much mpg am I gonna lose? I'm consistently getting 20.5 mpg right now with standard 18"

04-04-2013, 02:26 PM	#2
Angrybird 12 7 year Cancer Survivor! Drives: 17 Cruze RS, 07 G6 GT, 99 Astro Join Date: Dec 2007 Location: East Tennessee Posts: 21,547	Well you need to keep the rolling diameter the same to keep from changing your MPG. If you change rolling diameter of the tire/wheel combo you need to have the computer program changed to compensate on your MPH and Odo readings. Larger wheels and tires should actually increase your mpg because your gearing remains the same but it takes fewer revolutions per mile of the driveline. Your acceleration will suffer though. That being said if you stick to the stock GM tire sizes for the different size wheels you should not have to compensate and it should not effect your mileage. __________________ Cancer's a bitch! Enjoy life while you can! LIVE, LOVE, DRIVE... The Bird is the word!

04-04-2013, 02:48 PM	#4
OmniCamaro US Veteran Drives: 2011 Silver Ice Metallic 2SS/RS A6 Join Date: Jan 2011 Location: Bossier City, La Posts: 1,407	Your DIC will show worse gas mileage. How do I know? I put smaller tires on my rears(low profile) and my MPG went up quite a bit. You'll have to tune your gear ratio to fix it after changing. PM me if you need help. Also remember that the front tire diameter and the rear tire diameter have to be within a certain tolerance(sorry,I forget the number now) or your nannies will go nuts on you when you start driving. __________________ *Dear Lord, give me the strength to carry on despite my Camaro addiction!* JRE iTSX tune, full cat-less Dynatech exhaust, CAI intake, Stillen Slotted/Drilled Rotors, RB braided brake lines, BMR lowering springs, (reserved for definite future MODS)

04-05-2013, 04:23 PM	#7
intensifi Drives: '12 2LT Convertible Join Date: Mar 2012 Location: Belmont, California Posts: 1,701	more weight = less mileage An article on the new Z/28 in Consumer Reports stated the 19" inch wheels/tires weigh less than the 20" wheel/tires on the SS & ZL1 ( & RS ) http://news.consumerreports.org/cars...power-war.html I think what this means is if you could find a 19" or 20" wheel/tire combo that weigh the same as your 18"s there would be no difference. __________________ Mods: GM Locking Gas Cap, RS License Plate Frame, SS Brembos, ZL1 FrontEnd, 14/15 Convertible Top

04-04-2013, 02:44 PM	#3
Wilson_51 Drives: 2010 Lt Camaro Join Date: Apr 2013 Location: Arkansas Posts: 45 View My Garage	I have 22's on front and 24's on back and havent really noticed any change in MPG. Now my speedomoter was off 5, but i used my programmer and fixed that.

04-05-2013, 01:24 PM	#5
v6_camaro Drives: 2013 Camaro 1LS Join Date: Sep 2012 Location: California Posts: 31	I'm leaning toward 19" with 45 profile, would I get a slightly better mileage since the overall diameter is smaller than the stock 18"

04-05-2013, 04:49 PM	#8
Fish-man Drives: too many to say! Join Date: Nov 2010 Location: S.E. Michigan Posts: 1,013	Tires have several things that will affect mpg. 1-rolling resistance 2-width 3- Overall diameter 4-"weight" 1 is probably the most influential, but is also the one you wont find out unless you have a dyno that measures rolling resistance. Generally, moving from a all season tire to a summer performance tire will make for higher rolling resistance 2 if the tire gets wider, it makes the car have more frontal area... and therfore more drag 3 if the tire gets taller, it raises the car off the ground, and allows more air under the car, making mpg worse And a fourth, mass (rather rotational inertia), is probably harder to quantify, since the portion of driving that is stopping and starting is relativley small. Something that you can feel in accel/braking though.