08 Impreza 2.5i 4dr tire size

gingburg · 06-10-2009, 02:12 PM

So I just got the 07 WRX oem 17x7 wheels and I am awaiting installation, I assume they will fit fine on my 08 2.5i - correct me if I am wrong. But I was wondering what people thought of tire size. Will I be okay with 225/45/17 or do I need to go smaller. Everything is stock except I have pinks (springs), and sway bars (aftermarket). Thanks guys, ps i don't know anything about this stuff. Thank's.

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MYfirst00 · 06-12-2009, 07:50 AM

You'll be fine with 225s.

gingburg · 06-12-2009, 11:36 AM

Some people say that it will mess up the speedometer, or the suspension is not correct for this size. Any explanation. Thanks

MYfirst00 · 06-12-2009, 11:48 AM

Quote:

Originally Posted by gingburg

Some people say that it will mess up the speedometer, or the suspension is not correct for this size. Any explanation. Thanks

The only way you'd see a difference in your speedo is if you're going about 500 miles per hour. At any speed you're capable of with the car, whatever fraction in the sidewall height from stock is not going to be noticeable. I've had 215/50-17 on my Legacy (stock is 205/55-16) and there was no difference in my GPS calculated speed and my speedo. Your struts would be the same as a WRX, so you have the same amount of room within the perch height. And they run 205/50-17. 205/50 sidewall height it 102.5mm, and 225/45 sidewall height is 101.25mm. That's a difference of 1.25mm in height - hence no noticeable difference in speedo calculation. The difference in tread width at the top is 20mm, or 3/4". So the fact that your 225mm is sitting lower at the perch level is still well within spec since the perch gets wider as it goes lower to the strut.

Ryan

gingburg · 06-12-2009, 03:20 PM

so does the lower perch refer to the lowering springs the pinks, thank you for all your help.

MYfirst00 · 06-12-2009, 03:26 PM

The perch is the bottom cup of the strut that the springs sit on. Looks like a funnel. When you stick your finger at the inside top of the tire, that's where the perch is.

aba4430 · 06-13-2009, 11:01 AM

At an indicated 65 mph on 205/55/16 stock tires, you will be actually driving 65.25 mph on 225/45/17 tires, hardly a difference to be worried about. Is a 7" width wheel specidified for use with a 225 wide tire, make sure of this. I have not checked. Use this link to play around with various scenarios:

http://www.discounttiredirect.com/di...foTireMath.jsp

mosc · 06-13-2009, 02:00 PM

Spedo difference is misleading. Tires generally have about 11/32 of treadwear top and bottom. The difference between a worn tire and a new tire can be over a half an inch of overall diameter (~2% different than stock). Obviously there's some margin there anyway so don't sweat it. Within 2% is fine.

06-10-2009, 02:12 PM	#1
gingburg Scooby Newbie Member#: 195039 Join Date: Nov 2008	08 Impreza 2.5i 4dr tire size So I just got the 07 WRX oem 17x7 wheels and I am awaiting installation, I assume they will fit fine on my 08 2.5i - correct me if I am wrong. But I was wondering what people thought of tire size. Will I be okay with 225/45/17 or do I need to go smaller. Everything is stock except I have pinks (springs), and sway bars (aftermarket). Thanks guys, ps i don't know anything about this stuff. Thank's. * Registered users of the site do not see these ads.

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06-12-2009, 07:50 AM	#2
MYfirst00 Scooby Specialist Member#: 22928 Join Date: Aug 2002 Chapter/Region: NESIC Location: Fitchburg, MA Vehicle: 2011 Outback Sport Black	You'll be fine with 225s.

06-12-2009, 11:36 AM	#3
gingburg Scooby Newbie Member#: 195039 Join Date: Nov 2008	Some people say that it will mess up the speedometer, or the suspension is not correct for this size. Any explanation. Thanks

06-12-2009, 03:20 PM	#5
gingburg Scooby Newbie Member#: 195039 Join Date: Nov 2008	so does the lower perch refer to the lowering springs the pinks, thank you for all your help.

06-12-2009, 03:26 PM	#6
MYfirst00 Scooby Specialist Member#: 22928 Join Date: Aug 2002 Chapter/Region: NESIC Location: Fitchburg, MA Vehicle: 2011 Outback Sport Black	The perch is the bottom cup of the strut that the springs sit on. Looks like a funnel. When you stick your finger at the inside top of the tire, that's where the perch is.

06-13-2009, 11:01 AM	#7
aba4430 Scooby Newbie Member#: 211632 Join Date: May 2009 Location: Pace, FL Vehicle: 2008 Impreza OBS Ob black/DGM	At an indicated 65 mph on 205/55/16 stock tires, you will be actually driving 65.25 mph on 225/45/17 tires, hardly a difference to be worried about. Is a 7" width wheel specidified for use with a 225 wide tire, make sure of this. I have not checked. Use this link to play around with various scenarios: http://www.discounttiredirect.com/di...foTireMath.jsp

06-13-2009, 02:00 PM	#8
mosc Scooby Specialist Member#: 177401 Join Date: Apr 2008 Chapter/Region: Tri-State Location: Philly Vehicle: 2004 STi White 16G powered lagless fun	Spedo difference is misleading. Tires generally have about 11/32 of treadwear top and bottom. The difference between a worn tire and a new tire can be over a half an inch of overall diameter (~2% different than stock). Obviously there's some margin there anyway so don't sweat it. Within 2% is fine.