17" rims

viking64 · #1 04-15-2008, 06:40 AM

have found some rims that will fit in all areas except they are staggered.

Fronts are 7.5 with 48 offset

Rears are 8.5 with 55 offset

would there be any potential problems and if I went 225 - 45 - 17 both front and rear would not affect the AWD - or is the rear tyre too small for that rim?

Crazy_pilot · #2 04-15-2008, 09:28 PM

225 on a 17 is do-able, but not a good idea. The tire would be very stretched on the rim.

In general, different sized wheels are not a good idea on an AWD vehicle. One of the only ones I know that does it is the Jeep Cherokee SRT-8. I have one sitting in the shop right now, it has 9" wide rims front and 10" wide rear. The tire size for it is 255/45/20 front, and 285/40/20 rear. Those two tire sizes are withing 0.2% diameter of each other, so it's unlikely the transmission will suffer any harm.

If you really want to run different sized wheels, I would recommend 225/45/17 tires on the front and 255/40/17's on the rear. The diameter difference is the same as the Jeep's, 0.2% (4.7mm). I wouldn't lose sleep over such a small difference.

viking64 · #3 04-15-2008, 10:40 PM

[QUOTE=Crazy_pilot;541893]225 on a 17 is do-able, but not a good idea. The tire would be very stretched on the rim.

thanks Chris - not sure what you mean here.

original tyres were 225 - 50 on 16" , so if I was to look at 225 - 45 on 17" is not a good idea or just not a recomended size.?
And to clarify - if same size tyres are used front & rear, but rim at rear are 1" wider does this effect the tyre diameter? or are you saying the wider rims would need wider tyre.?

GreenMarine · #4 04-15-2008, 10:51 PM

Quote:

Originally Posted by Crazy_pilot

225 on a 17 is do-able, but not a good idea. The tire would be very stretched on the rim.

In general, different sized wheels are not a good idea on an AWD vehicle. One of the only ones I know that does it is the Jeep Cherokee SRT-8. I have one sitting in the shop right now, it has 9" wide rims front and 10" wide rear. The tire size for it is 255/45/20 front, and 285/40/20 rear. Those two tire sizes are withing 0.2% diameter of each other, so it's unlikely the transmission will suffer any harm.

If you really want to run different sized wheels, I would recommend 225/45/17 tires on the front and 255/40/17's on the rear. The diameter difference is the same as the Jeep's, 0.2% (4.7mm). I wouldn't lose sleep over such a small difference.

Crazy Pilot... You really ARE crazy aren't you... I have no idea what you are talking about when you are saying that 225's are not a good idea on 17" wheels... You do know that 225 is the WIDTH of the tire right?? Plenty of cars come with 17" wheels and 225 tires... The 2004 WRX STi for example... Do alittle reading before giving a n00b advice on tires...

Another thing... The AWD system in the SVX and the (whatever the hell kinda AWD system it has) one in the Jeep SRT-8 are two totally different animals... So altering the tire size on the Jeep may do nothing, where as in our cars, you might be looking for a new Center Diff...

And why are you recommending someone run different sized tires on a Subaru???

~ Chris

GreenMarine · #5 04-15-2008, 10:55 PM

Quote:

Originally Posted by viking64

have found some rims that will fit in all areas except they are staggered.

Fronts are 7.5 with 48 offset

Rears are 8.5 with 55 offset

would there be any potential problems and if I went 225 - 45 - 17 both front and rear would not affect the AWD - or is the rear tyre too small for that rim?

[QUOTE=viking64;541923]

Quote:

Originally Posted by Crazy_pilot

225 on a 17 is do-able, but not a good idea. The tire would be very stretched on the rim.

thanks Chris - not sure what you mean here.

original tyres were 225 - 50 on 16" , so if I was to look at 225 - 45 on 17" is not a good idea or just not a recomended size.?
And to clarify - if same size tyres are used front & rear, but rim at rear are 1" wider does this effect the tyre diameter? or are you saying the wider rims would need wider tyre.?

Viking64 - Dude, if I were you I would NOT buy those wheels and DEFINITELY don't listen to anything in that first reply to your original post, unless you want to screw up your tranny...

Look for wheels that are EXACTLY THE SAME SIZE.... Then Buy tires that are EXACTLY THE SAME SIZE and you will be alright... Anyone who tells you otherwise doesn't know what in the world they are talking about...

But don't believe me, research Subaru transmissions and read about what causes diff failures... Then research how much it will cost to have the Center diff replaced...

Good luck making the right decision...

~ Chris

GreenMarine · #6 04-15-2008, 11:00 PM

Quote:

Originally Posted by viking64

have found some rims that will fit in all areas except they are staggered.

Fronts are 7.5 with 48 offset

Rears are 8.5 with 55 offset

would there be any potential problems and if I went 225 - 45 - 17 both front and rear would not affect the AWD - or is the rear tyre too small for that rim?

To answer this question... In my oppinion, YES the rear wheel would be too big for the tire... For an 8.5" wide wheel you'll want something like 245 or 255 in width... Not to mention they would look retarded even if they could work... Just do yourself a favor and get rid of the staggered rims... They will cause a headache and also won't allow you to rotate your tires as they wear, costing you yet more $$$ in the long run...

~ Chris

viking64 · #7 04-15-2008, 11:15 PM

thanks Chris aka GreenMarineSVX,

your response makes much more sense and quite logical considering the problems known to the transmission and drivetrain issues on Subies.

You basically had confirmed what I was thinking.

In the past it has been easy - as you just replace the tyres when they wear out - but since my rims were stolen I need to find replacements and the offset/stud pattern we use is not all that common.

Thanks for the advice

bruce

GreenMarine · #8 04-16-2008, 12:14 AM

Quote:

Originally Posted by viking64

thanks Chris aka GreenMarineSVX,

your response makes much more sense and quite logical considering the problems known to the transmission and drivetrain issues on Subies.

You basically had confirmed what I was thinking.

In the past it has been easy - as you just replace the tyres when they wear out - but since my rims were stolen I need to find replacements and the offset/stud pattern we use is not all that common.

Thanks for the advice

bruce

Hell, if you were closer I'd sell you my stockers from my 1995 SVX... There are a few good wheels that you can use out there... Just search the members photo thread in the General SVX forum... Look through the pictures for wheels you like... Then PM the person who posted the pic and ask them what wheels and specs they are

I believe you can run up to a 245 tire on the SVX without rubbing issues in the rear... Don't quote me on that as I am on 225's at the moment.

~ Chris

Crazy_pilot · #9 04-16-2008, 08:06 PM

YIKES!!

I meant 225 (yes, I know, width in millimeters as measured on a certain rim at the tire's widest point) on an 8.5" wide rim will be stretched.

This is a stretched tire:

Notice how the sidewalls are very angled inwards toward the tread. That's what happens when the tire is too narrow for the rim. Do-able, but not a good thing. Looks stupid too.

As for giving "n00b" advice, I work at a high performance tire shop. I've put more Z rated tires on things with over 400 HP than I can remember.

Let's do some math: 4.7 mm overall diameter difference between a 225/45/17 and a 255/40/17. For overall circumferance, multiply by pi, giving us 14.8 mm additional rolling circumferance. So every time the wheels go around one will try to move 0.58 inches farther than the other one. Now let's assume you're running a Goodyear Eagle F1 GS-D3 tire. This tire, in the 225/45/17 size, rotates 837 times per mile, as given by the manufacturer. So this means that every mile, one axle will try to rotate 40.455 feet more than the other. Ah nuts, new tranny time.

I've seen bad alignements that will cause more of a difference than that. Simply running your tires at 35 PSI all around instead of a 3 PSI difference front/rear will cause more than that. In the suggestion I gave, the 255 wide tire is the taller of the two, so boost the PSI difference slightly and voila! the same rolling diameter!

Now all of this is kind of silly, because if you look at my original post, you will see that I say:

Quote:

In general, different sized wheels are not a good idea on an AWD vehicle....If you really want to run different sized wheels...

No where in there do I say YA SURE! GO FOR IT!! I said it's not a good idea, but if your heart is set on running different sized wheels, this is my advice. The fact that I made a typo seems to have given license for you to hammer me.

Any more questions?