adding smaller tires than stock can change ur MPG?
02-07-2005, 04:45 PM
#1
Senior Member
Thread Starter
Join Date: Oct 2004
Posts: 165
Likes: 0
Received 0 Likes
on
0 Posts
adding smaller tires than stock can change ur MPG?
my civic has 195/60/14 but the tires threads are bad i have a crx with ghood tires but its 175/70/14 if i was so swap them (rims included) would this make the MPG worse or not change at all?
02-07-2005, 05:08 PM
#4
HAN Approved Vendor
Join Date: Mar 2004
Posts: 357
Likes: 0
Received 0 Likes
on
0 Posts
The diameter of the 175=23.6 in
The diameter of the 195=23.2 in
soo a net difference of less than 1/2 in.
Being that the 175's would spin slower, they, in theory would net greater fuel economy becuase your motor would be seeing less revs.
However this is only on paper.. There are way to many other variables to be sure..
For example, eventhough the 175 rotates @ slower rate, you may end up applying more throttle to get the car up to speed becuase it no longer has the proper gearing.. perhaps, to make it up hills etc.
We could go even further, into rolling resistance (the 175's should have less because they are more narrow than the 195), inertia of the tirewheel system, energy lost due to tire deflection, etc, etc etc.
What I'm getting @ is their may not really be any noticeable difference, the best thing to do is try both and record results..
Also, here is a helpful tire size calc
http://www.miata.net/garage/tirecalc.html
The diameter of the 195=23.2 in
soo a net difference of less than 1/2 in.
Being that the 175's would spin slower, they, in theory would net greater fuel economy becuase your motor would be seeing less revs.
However this is only on paper.. There are way to many other variables to be sure..
For example, eventhough the 175 rotates @ slower rate, you may end up applying more throttle to get the car up to speed becuase it no longer has the proper gearing.. perhaps, to make it up hills etc.
We could go even further, into rolling resistance (the 175's should have less because they are more narrow than the 195), inertia of the tirewheel system, energy lost due to tire deflection, etc, etc etc.
What I'm getting @ is their may not really be any noticeable difference, the best thing to do is try both and record results..
Also, here is a helpful tire size calc
http://www.miata.net/garage/tirecalc.html
Last edited by FunctionMotoring; 02-07-2005 at 05:11 PM.
02-08-2005, 12:23 AM
#5
Registered User
Join Date: Jul 2004
Posts: 317
Likes: 0
Received 0 Likes
on
0 Posts
yes it can change a little cause i have that setup in my car. its a 94 civic coupe, had stock 14's on, which is 195/60/14, and i switched to my old 90 civic's stock rims, 175/70/13, only to the front 2 rims tho. i noticed acceleration was a bit better, and i went from 31 mpg to about 33.
02-08-2005, 06:55 AM
#6
The difference will be very little, and hard to measure. Even if you check mpg I wouldn't expect it to change more than 1 or 2 mpg. Even then you could factor in different gas, difference in air temperature, age of the oil, wind, not to mention road variation. Even on an oval track test there would be too many variables.
02-08-2005, 07:13 AM
#7
HAN Approved Vendor
Join Date: Mar 2004
Posts: 357
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by oldskoolcivic
yes it can change a little cause i have that setup in my car. its a 94 civic coupe, had stock 14's on, which is 195/60/14, and i switched to my old 90 civic's stock rims, 175/70/13, only to the front 2 rims tho. i noticed acceleration was a bit better, and i went from 31 mpg to about 33.
02-08-2005, 12:37 PM
#8
Registered User
Join Date: Jul 2004
Posts: 317
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by FunctionMotoring
Acceleration should have been worse... Unless the 175's were much lighter.
it was actually better, the stock 14's weighed 18 pounds, and the stock 13's weighed 16. less rotating mass or some shit
02-08-2005, 12:41 PM
#9
Senior Member
Join Date: May 2003
Posts: 2,124
Likes: 0
Received 0 Likes
on
0 Posts
I don't think u would have a noticeable difference in mpg however having better tires would be good anyways in case u run into bad weather depending on what part of the country you are from
