Welcome to the North American Subaru Impreza Owners Club Wednesday May 23, 2018
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...
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 04-20-2006, 07:19 PM   #1
kleggo
Scooby Newbie
 
Member#: 105294
Join Date: Jan 2006
Location: carlsbad ca
Default permissable Effective Wheel / Tire Diameter changes?

Yes, i did search and i did read the FAQs which had lottsa good info, but not specifically what i'm looking for.

now that that's out of the way

I'm buying aftermarket wheels / tires for my 06 LL Beanie.
It's my understanding that with the AWD, i should maintain nearly the same Effective Wheel / Tire Diameters at all four corners to keep things happy.

My question is, how far from the nominal diameter of the existing wheel / tire combo can i deviate as far as the AWD system is concerned?
I'm looking to fill the wheelwells a bit more without lowering the car.

I realize that changing EWD may effect tire / body clearance and speedo reading.
i know that wheelwell opening size limits EWD.
How much larger can i go before the AWD drive or any associated sensors freak out?
Does a 1 or 2" increase screw with the AWD sensors?

thank you

be safe

kleggo
* Registered users of the site do not see these ads.
kleggo is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 04-20-2006, 07:23 PM   #2
WrexT
Scooby Newbie
 
Member#: 80169
Join Date: Jan 2005
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 PSM WRX
Cobb Stage 2 biotch!

Default

A lot of guys here are running tires close to 1" taller than stock and I have yet to hear of a problem (in regards to ABS/AWD and such). It's not the proper way to tire our cars, but people are doing it! The usual recommendation is to stay within 2-3% of OE overall diameter.
WrexT is offline   Reply With Quote
Old 04-20-2006, 07:56 PM   #3
waktasz
Scooby Guru
 
Member#: 86356
Join Date: May 2005
Chapter/Region: Tri-State
Vehicle:
2016 Aprilia
Tuono v4 1100 Factory

Default

As long as they fit in your wheel wells you can run whatever size tires you want. The AWD doesn't like tires that are of varying size (like 225/45 front 245/45 rear) or something. Going to 4 larger tires won't change anything except your speedo/odo readings.
waktasz is offline   Reply With Quote
Old 04-20-2006, 10:43 PM   #4
kleggo
Scooby Newbie
 
Member#: 105294
Join Date: Jan 2006
Location: carlsbad ca
Default

Quote:
Originally Posted by waktasz
As long as they fit in your wheel wells you can run whatever size tires you want. The AWD doesn't like tires that are of varying size (like 225/45 front 245/45 rear) or something. Going to 4 larger tires won't change anything except your speedo/odo readings.
__________________________________________________ ______________

thank you for the cogent reply.

blue skies

Craig
kleggo is offline   Reply With Quote
Old 04-20-2006, 11:50 PM   #5
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Quote:
Originally Posted by waktasz
As long as they fit in your wheel wells you can run whatever size tires you want. The AWD doesn't like tires that are of varying size (like 225/45 front 245/45 rear) or something. Going to 4 larger tires won't change anything except your speedo/odo readings.

...AND it will KILL----destroy is a better word....your acceleration and torque.....it will be a complete slug if you put such tall wheels on it and your braking and fuel mileage will suffer as well, due to the incerased weight.


Great idea.
Uncle Scotty is offline   Reply With Quote
Old 04-21-2006, 12:19 AM   #6
Patrick Olsen
NASIOC Supporter
 
Member#: 120
Join Date: Jul 1999
Chapter/Region: AKIC
Location: Where the Navy sends me...
Vehicle:
1997 Legacy 2.5GT
1996 Impreza coupe

Default

Yeah, but it'll look better, and that's all that matters, bro!
Patrick Olsen is offline   Reply With Quote
Old 04-21-2006, 12:58 AM   #7
WrexT
Scooby Newbie
 
Member#: 80169
Join Date: Jan 2005
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 PSM WRX
Cobb Stage 2 biotch!

Default

Quote:
Originally Posted by Patrick Olsen
Yeah, but it'll look better, and that's all that matters, bro!
You're crazy....Do it right, put the proper height tire on there and lower it!
Don't cut corners buddy!
WrexT is offline   Reply With Quote
Old 04-21-2006, 01:21 AM   #8
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Uncle Scotty is offline   Reply With Quote
Old 04-21-2006, 01:22 AM   #9
Back Road Runner
Scooby Guru
 
Member#: 60082
Join Date: Apr 2004
Chapter/Region: MWSOC
Location: Minnesota
Vehicle:
2004 Forester STI
Silver

Default

Doesn't matter.

Just realize the limits in physical space, primarily the struts. You can only go so wide and so tall. The sad part is you're basically stuck at stock as pretty close to the maximum. On my '02 Forester, stock size being 215/60/R16, I'm basically limited to that size. Any wider, I rub the rear strut, any taller, I rub the spring perch(think that's what you call it). Sure you have a few milimeters to work with, but you're basically set to max at the start.

How to fix this?

Lift kit, coilovers, lower offset wheels, each with their own benifits and downsides. You figure out how you want to go about doing things.


As far as adverse effects with a different diameter tire, everyone else basically covered that. Your car and all it's electronics don't care...as long as all 4 are the same size.
Back Road Runner is offline   Reply With Quote
Old 04-21-2006, 12:17 PM   #10
kleggo
Scooby Newbie
 
Member#: 105294
Join Date: Jan 2006
Location: carlsbad ca
Default

Quote:
Originally Posted by Uncle Scotty
...AND it will KILL----destroy is a better word....your acceleration and torque.....it will be a complete slug if you put such tall wheels on it and your braking and fuel mileage will suffer as well, due to the incerased weight.


Great idea.
__________________________________________________ _______________
i know it is, that's why i'm doing it.

If you read carefully you probably noticed that it's a LL Bean wagon.
How high up on the list do you think acceleration and torque is on my list of gotta haves for this car?

I drive my Cayman S when i want performance, not a station wagon

PS Torque is not a function of tire diameter.
Torque = the rotational equivalent of a force, and is calculated by multiplying the force causing rotation by the perpendicular distance from the line of action of the force to the centre of rotation. The unit is the newton metre.

What you percieve as Torque is affected by tire diameter, but Torque ( the force produced by the engine [not motor] is not).

have fun and thanks for the kind words.

be safe

kleggo
kleggo is offline   Reply With Quote
Old 04-21-2006, 01:43 PM   #11
UltimateLurker
Scooby Guru
 
Member#: 82488
Join Date: Mar 2005
Chapter/Region: MWSOC
Location: Missouri
Vehicle:
06 Lotus Exige

Default

Quote:
Originally Posted by waktasz
As long as they fit in your wheel wells you can run whatever size tires you want. The AWD doesn't like tires that are of varying size (like 225/45 front 245/45 rear) or something. Going to 4 larger tires won't change anything except your speedo/odo readings.
Exactly.

Quote:
Originally Posted by Uncle Scotty
...AND it will KILL----destroy is a better word....your acceleration and torque.....it will be a complete slug if you put such tall wheels on it and your braking and fuel mileage will suffer as well, due to the incerased weight.


Great idea.
You're confused, but I'm glad you think you know what you're talking about. If this is true, explain the performance #'s of the WR1. I know, I know, you're absolutely clueless as to what I'm talking about, hmmm, see a pattern here?


Quote:
Originally Posted by kleggo
PS Torque is not a function of tire diameter.
Torque at the wheels most certainly is, or rather, the practical application of engine torque is, don't make me explain it to you. However, for your application, I say g'head, you should be fine (but you knew that before you even started the thread).

.
UltimateLurker is offline   Reply With Quote
Old 04-21-2006, 03:23 PM   #12
kleggo
Scooby Newbie
 
Member#: 105294
Join Date: Jan 2006
Location: carlsbad ca
Default

Torque at the wheels most certainly is, or rather, the practical application of engine torque is, don't make me explain it to you. However, for your application, I say g'head, you should be fine (but you knew that before you even started the thread).

.[/quote]
__________________________________________________ _______________
UL
you are correct. hmmmmmm that seems to happen frequently.

i should have more clearly stated that ENGINE torque is not a function of tire diameter.
Resultant torque applied the Outside Diameter of the wheel / tire is most certainly a function of O.D.

be safe

kleggo
kleggo is offline   Reply With Quote
Old 04-21-2006, 03:46 PM   #13
ricardo
Scooby Newbie
 
Member#: 64735
Join Date: Jun 2004
Location: Southern England
Vehicle:
2006 Forester STi
Black

Default

The difference in torque at the wheels due to bigger wheels is no different in principle from the difference caused by a different final drive ratio.

The idea of killing the torque would only apply if the car had just the one fixed gear - having a selection of gears means that the gear selection and the point at which gear-changes occur will change slightly. That's all...

The car will go faster in each gear before it runs out of revs. Not such a bad thing.
ricardo is offline   Reply With Quote
Old 04-22-2006, 12:24 AM   #14
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

....and people will continue to do stupid things to nice cars every day.



....and the ll beaner is a slug to start with----magnifying that isn't the best idea, IMO...especially if ya drive it on the highway and have to merge or pass somebody.

....and I(very unfortunatly) have to 'dumb down' all too often, here, so that the deeeeeeeeeeeeewwwwwwwwwwwwwwwwwds have some hope of gleaning any possible utility from any of my posts...so if ya wanna pick apart what I post.....piss off.
Uncle Scotty is offline   Reply With Quote
Old 04-22-2006, 05:49 AM   #15
ricardo
Scooby Newbie
 
Member#: 64735
Join Date: Jun 2004
Location: Southern England
Vehicle:
2006 Forester STi
Black

Default

Quote:
Originally Posted by Uncle Scotty
....and I(very unfortunatly) have to 'dumb down' all too often, here, so that the deeeeeeeeeeeeewwwwwwwwwwwwwwwwwds have some hope of gleaning any possible utility from any of my posts...so if ya wanna pick apart what I post.....piss off.
Ah, so this isn't an open forum then, I didn't notice that at first.
So am I allowed to ask how fuel mileage is made worse by taller gearing ?
ricardo is offline   Reply With Quote
Old 04-22-2006, 10:18 AM   #16
WrexT
Scooby Newbie
 
Member#: 80169
Join Date: Jan 2005
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
2004 PSM WRX
Cobb Stage 2 biotch!

Default

lock thread!
WrexT is offline   Reply With Quote
Old 04-22-2006, 02:16 PM   #17
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Quote:
Originally Posted by ricardo
Ah, so this isn't an open forum then, I didn't notice that at first.
So am I allowed to ask how fuel mileage is made worse by taller gearing ?

...the taller gearing isn't the issue it is rotational mass.....MUCH heavier and moved away from the axle mass is harder to get moving and to STOP moving once in motion.

If all ya did was drive on the highway....it may not be bad....but in all in town driving would be problematic.

Look at all the kiddie/ghetto hoopties runnin around on their lame assed dub-dubs....they get BAD mpg and eat brakes...ever wonder why???

Last edited by Uncle Scotty; 04-22-2006 at 02:22 PM.
Uncle Scotty is offline   Reply With Quote
Old 04-22-2006, 02:22 PM   #18
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Quote:
Originally Posted by WrexT
lock thread!

...why....did I offend you???

'cuz if I did....I made my point, right???

This boards decline and the continuing decline in age and apparent education of its members is glaringly apparent to me....hence my 'dumbing down' to the mentality of its mean members.

koo
Uncle Scotty is offline   Reply With Quote
Old 04-22-2006, 04:12 PM   #19
ricardo
Scooby Newbie
 
Member#: 64735
Join Date: Jun 2004
Location: Southern England
Vehicle:
2006 Forester STi
Black

Default

I agree on the rotational inertia. In this case it is more tire, not more wheel, but an increase in rotational inertia will have the effect you describe in stop-start traffic.

I spend more time driving at constant speed, so for me the taller gearing from the taller tires would give me a fuel mileage improvement if I wanted.

Which effect predominates depends of course on all the other factors...

Interestingly, the Impreza WR1 in the UK has a 225/45 tire instead of a 225/40-17, chosen by Subaru UK for that particular special edition. That's an inch taller in overall diameter, and I don't suppose they did it to make it slower.

Anyway, time to piss off I think.
ricardo is offline   Reply With Quote
Old 04-22-2006, 04:18 PM   #20
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Quote:
Originally Posted by ricardo
I agree on the rotational inertia. In this case it is more tire, not more wheel, but an increase in rotational inertia will have the effect you describe in stop-start traffic.

I spend more time driving at constant speed, so for me the taller gearing from the taller tires would give me a fuel mileage improvement if I wanted.

Which effect predominates depends of course on all the other factors...

Interestingly, the Impreza WR1 in the UK has a 225/45 tire instead of a 225/40-17, chosen by Subaru UK for that particular special edition. That's an inch taller in overall diameter, and I don't suppose they did it to make it slower.

Anyway, time to piss off I think.
...my initial comment was not directed, particularly, toward you...moreso toward UL....'cuz he can be a pain in the ass


.....and there are VERY few 225/40 tyres available..
Uncle Scotty is offline   Reply With Quote
Old 04-22-2006, 04:47 PM   #21
ricardo
Scooby Newbie
 
Member#: 64735
Join Date: Jun 2004
Location: Southern England
Vehicle:
2006 Forester STi
Black

Default

Quote:
Originally Posted by Uncle Scotty
.....and there are VERY few 225/40 tyres available..
It can be worse - our household is blessed with two Forester STi's(*) and one RX8. All take 225/45-18. That pretty much means Bridgestones, not my preferred choice for UK roads and UK weather. More choice in 225/40-18 than that, and much more in 235/40, which is where I may be headed. At least one tire size fits all the cars...

* One in a showroom for sale, the other one delivered from Japan but yet to be registered, neither of them available for me to drive at the time of writing
ricardo is offline   Reply With Quote
Old 04-22-2006, 11:00 PM   #22
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

....225/40-17 is what I was thinking.....and using a 225/40-18 in place of a 225/45-18 would make VERY little difference in any meaningful way, other than shortening the gear a bit
Uncle Scotty is offline   Reply With Quote
Old 04-22-2006, 11:26 PM   #23
waktasz
Scooby Guru
 
Member#: 86356
Join Date: May 2005
Chapter/Region: Tri-State
Vehicle:
2016 Aprilia
Tuono v4 1100 Factory

Default

^^^ He ninja editted that above post. At first he didn't say anything about 18s.

I got your back Scotty.
waktasz is offline   Reply With Quote
Old 04-23-2006, 01:37 AM   #24
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

.....meh....no matter......as long as everybody thinks I'm not tryin ta pick a fight or piss off the wrong person, here
Uncle Scotty is offline   Reply With Quote
Old 04-23-2006, 01:11 PM   #25
Assassin4457
Scooby Specialist
 
Member#: 96773
Join Date: Sep 2005
Chapter/Region: E. Canada
Location: GTA, Ontario Canada.
Vehicle:
04 WRX, RIP GC8
Black

Default

So the speed and odo readings change when you get a bigger wheel for example, how to change them to be back to accurate ?
Assassin4457 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
Changing tire diameter = different gearing BUT..... reddevil Proven Power Bragging 14 07-30-2006 03:57 AM
Changing overall wheel/tire diameter I_smoke_hondas Tire & Wheel 1 11-14-2003 02:02 PM
Effect of wider wheel? (same diameter and weight) pdlindor Tire & Wheel 3 08-01-2003 10:03 AM
Cost-effectiveness of tires & wheels? Noots Brakes, Steering & Suspension 5 09-25-2001 02:45 AM

All times are GMT -4. The time now is 08:12 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.