Welcome to the North American Subaru Impreza Owners Club Monday December 29, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Click here to visit TireRack
Tire & Wheel Forum sponsored by The Tire Rack

Losing traction? Need new tires?
Click here to visit the NASIOC Upgrade Garage...
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Tire & Wheel

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 02-10-2007, 12:35 PM   #1
metoo
Scooby Guru
 
Member#: 4764
Join Date: Mar 2001
Chapter/Region: TXIC
Location: Houston
Vehicle:
2004 STi sold :(
forizzle

Default 225/40/18 vs 235/40/18

Weights specified are all for the same tire brand and model
I will be putting these on 18x7.5 wheels. Edit 235s should be on at least 8" rims.

225/45/17 stock size for reference
weight (lbs) per tire: 23.7 = 94.8 for four tires
weight for RE070: 27 (info from one uncredited resource)
diameter (in): 24.97
circumference (in): 78.45


225/40/18
weight (lbs) per tire: 23.6 = 94.4 for four tires
diameter (in): 25.07
circumference (in): 78.81
Advantages over 235/40/18:
*Will not noticeably effect gas mileage or gauges based diameter alone
*should have a less flexible side wall
*$23 per tire cheaper for this particular tire.
*lighter than stock size and nearly 9 lbs lighter than the compared tire size set, making for less mass to accelerate and deccelerate.
*lower profile looks better from the side
*less chance of hydroplaning


235/40/18
weight (lbs) per tire: 25.8 = 103.2 for four tires
diameter (in): 25.40
circumference (in): 79.80
Advantages over 225/40/18:
*will fill the wheel well better
*wider look betters from views other than the side.
*better wheel protection laterally and vertically
*technically softer ride (but doubtfully noticeable)
*probably better mid and top end acceleration with my GT30R setup
*wider means more grip on dry road for cornering, acceleration, and braking


What about gas mileage? Upon acceleration, the 225 has an obvious avantage. It has a smaller diameter and a less rotating mass. At cruise, I'm not sure which wins out. The 235 would cover more ground per revolution, but does the engine require more effort move the 235 a mile. The 235 has greater rolling resistance and greater frontal area (less wind resistance).

I'm just not sure whos avantages are better.
What are your thoughts.
* Registered users of the site do not see these ads.

Last edited by metoo; 02-11-2007 at 04:00 PM.
metoo is offline   Reply With Quote
Old 02-10-2007, 01:02 PM   #2
waktasz
Scooby Guru
 
Member#: 86356
Join Date: May 2005
Chapter/Region: Tri-State
Default

Most (all?) 235/40-18s list 8" as the minimum width...I'm sure you could get them on there, but would they look bulged? Dunno.
waktasz is offline   Reply With Quote
Old 02-10-2007, 03:06 PM   #3
metoo
Scooby Guru
 
Member#: 4764
Join Date: Mar 2001
Chapter/Region: TXIC
Location: Houston
Vehicle:
2004 STi sold :(
forizzle

Default

Quote:
Originally Posted by waktasz View Post
Most (all?) 235/40-18s list 8" as the minimum width...I'm sure you could get them on there, but would they look bulged? Dunno.
Thanks for the info. It seems you're right.

For 235/40/18:
Kumho says 7.5-9
Falken says 8.0-9.5
Fuzion says 8.0-9.5
Toyo says 8.0-9.5

What I don't understand is why the size range goes down a given width on 17's. For examle a 225/45/17 Falken Azenis calls for a 7.0-8.5 wheel. The same tire in a 225/40/18 calls for a 7.5-9 wheel. I guess the reason is, for a given width, the shorter side the wall the greater the angle of the wall would be to the bead seat of the wheel as you decress wheel width.

I guess I'm stuck with the 225s, but this is still a good thread for those with 8" wheels.
metoo is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
235/40/17 vs. 235/40/18 purduephigam Tire & Wheel 52 12-05-2006 11:51 PM
225/40/18 Great Tires vs 235/40/18 Good Tires JxOxExY Tire & Wheel 18 04-04-2006 05:12 PM
225/40/18 or 235/40/18 jland67 Tire & Wheel 2 05-19-2005 12:15 PM
225/45/17 vs 235/40/17 atomicapples Tire & Wheel 6 06-16-2004 11:01 AM
225/40-18 or 235/40-18 paikia Tire & Wheel 6 10-22-2003 12:39 PM


All times are GMT -4. The time now is 10:07 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.