Another Rim/wheel question..SORRY!
#21
08-22-2007 | 04:34 PM
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Joined: Mar 2007
Posts: 8,666
From: Manor, TX (Outside of Austin)
RE: Another Rim/wheel question..SORRY!
SST, I think you and I are comparing apples and oranges here...
It seems from what you are saying that you are talking about backspacing, which may indeed be a problem he might come across using an 8" wheel.
I was addressing the offset of the wheels he's looking at. Offset (I'm sure you already know this) is the difference between to centerline of the wheel and the mounting surface (52.5/25.4= 2.0669",) so that should remain consistent from wheel to wheel on a given car... assuming your not driving a Porsche 911 with different offsets and wheel widths front to back.
Afterall, why would the MS guys suggest a +52.5 on a 7.5" wheel when the same offset is used on the 6.5" wheel?
Am I correct... that we are talking about two potentially different issues?
#22
08-22-2007 | 07:00 PM
Senior Member
Joined: Nov 2005
Posts: 2,612
RE: Another Rim/wheel question..SORRY!
ORIGINAL: dentinger
so.... are you saying that a 18x8 inch rim, with a +45 offset, with 215/40/18 rubber will be fine???
p.s. i got me some prices on those rims too
the rims (either ones) are $1150/set
the tires are anywhere form $850 - $1000/set
(cdn dollars, btw)
so.... are you saying that a 18x8 inch rim, with a +45 offset, with 215/40/18 rubber will be fine???
p.s. i got me some prices on those rims too
the rims (either ones) are $1150/set
the tires are anywhere form $850 - $1000/set
(cdn dollars, btw)
Go out to your car with a ruler (roughly 1" wide & 12" long) Placethe thin edgeagainst the edge of your tire/wheel vertically so that it goes up and contacts your wheelwell lip, with the 1" thickness spanning the distance from your tire to the wheelwell. Does it hit the sheetmetal or does it clear?
#23
08-22-2007 | 07:07 PM
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Joined: Nov 2005
Posts: 2,612
RE: Another Rim/wheel question..SORRY!
Thefriend's recommendation was based on the widest rim that would fit. They did a fitment study and that was the best size...that is why the Mazdaspeed wheels come in those sizes/offsets, because they are the optimal solution between size and fitment/clearance.
backspacing vs. offset....2 ways to measure the same thing.
Backspacing is the distance from the back edge of the wheel to the mounting surface
Offset is the distance from the centerline of the wheel to the mounting surface of the wheel.
Backspacing is easier for a person to measure at home, but few wheel mfg list the backspacing of their wheels, they list offset.
I'm giving him reference points that he can see on his car to judge whether or not they would fit (namely the outer edge distance being defined as that is what would contact the wheelwell in the rear)
You would maintain the offset of the wheel, even though you are going wider to try to split the added width across both the inside and outside edges of the wheel. (52.5 offset on a 7.5" wheel has 1/2" of width added to both the inside and outside edges when compared to a 6.5" wheel of the same offset.)
backspacing vs. offset....2 ways to measure the same thing.
Backspacing is the distance from the back edge of the wheel to the mounting surface
Offset is the distance from the centerline of the wheel to the mounting surface of the wheel.
Backspacing is easier for a person to measure at home, but few wheel mfg list the backspacing of their wheels, they list offset.
I'm giving him reference points that he can see on his car to judge whether or not they would fit (namely the outer edge distance being defined as that is what would contact the wheelwell in the rear)
You would maintain the offset of the wheel, even though you are going wider to try to split the added width across both the inside and outside edges of the wheel. (52.5 offset on a 7.5" wheel has 1/2" of width added to both the inside and outside edges when compared to a 6.5" wheel of the same offset.)
#24
08-22-2007 | 09:51 PM
Senior Member
Joined: Oct 2006
Posts: 1,460
RE: Another Rim/wheel question..SORRY!
i just pm'd one of the guys on the tm3 boards.
he has 18x8 rims, with a 45 offset, lowered on tein basics, with 215/40/18 rubber. stretched. lol
hes had numerous rims (i think4 sets so far this year) so im going to see if he can give me a definate answer.
he has 18x8 rims, with a 45 offset, lowered on tein basics, with 215/40/18 rubber. stretched. lol
hes had numerous rims (i think4 sets so far this year) so im going to see if he can give me a definate answer.
#25
08-23-2007 | 07:07 PM
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Joined: Mar 2007
Posts: 8,666
From: Manor, TX (Outside of Austin)
RE: Another Rim/wheel question..SORRY!
ORIGINAL: sstlaure
Thefriend's recommendation was based on the widest rim that would fit. They did a fitment study and that was the best size...that is why the Mazdaspeed wheels come in those sizes/offsets, because they are the optimal solution between size and fitment/clearance.
backspacing vs. offset....2 ways to measure the same thing.
Backspacing is the distance from the back edge of the wheel to the mounting surface
Offset is the distance from the centerline of the wheel to the mounting surface of the wheel.
Backspacing is easier for a person to measure at home, but few wheel mfg list the backspacing of their wheels, they list offset.
I'm giving him reference points that he can see on his car to judge whether or not they would fit (namely the outer edge distance being defined as that is what would contact the wheelwell in the rear)
You would maintain the offset of the wheel, even though you are going wider to try to split the added width across both the inside and outside edges of the wheel. (52.5 offset on a 7.5" wheel has 1/2" of width added to both the inside and outside edges when compared to a 6.5" wheel of the same offset.)
Thefriend's recommendation was based on the widest rim that would fit. They did a fitment study and that was the best size...that is why the Mazdaspeed wheels come in those sizes/offsets, because they are the optimal solution between size and fitment/clearance.
backspacing vs. offset....2 ways to measure the same thing.
Backspacing is the distance from the back edge of the wheel to the mounting surface
Offset is the distance from the centerline of the wheel to the mounting surface of the wheel.
Backspacing is easier for a person to measure at home, but few wheel mfg list the backspacing of their wheels, they list offset.
I'm giving him reference points that he can see on his car to judge whether or not they would fit (namely the outer edge distance being defined as that is what would contact the wheelwell in the rear)
You would maintain the offset of the wheel, even though you are going wider to try to split the added width across both the inside and outside edges of the wheel. (52.5 offset on a 7.5" wheel has 1/2" of width added to both the inside and outside edges when compared to a 6.5" wheel of the same offset.)
but have to disagree with you that backspacing and offset are two different ways of measuring the same thing.Offset = Constant.
Backspacing =Variable. Dependson wheel width.
#26
08-23-2007 | 07:59 PM
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Joined: Nov 2005
Posts: 2,612
RE: Another Rim/wheel question..SORRY!
When I say they are (2) ways of measuring the same thing , I mean that they both define a relationship between a reference point on the wheel and the mounting surface of the wheel.
For example: using an 18x8 wheel with the mounting surface right in the center of the wheel
The wheel would have a backspace of 4", and an offset of (0)
Now move the mounting surface out 50mm (approx 2") towards the outside of the vehicle
The 18x8 wheel would now have backspacing of 6" or an offset of 50mm (Mounting surface is 6" from back edge of wheel, and 2" from centerline of wheel)
Offset is just as variable as backspacing. That's why you see some wheels offered in many different offsets for the same width wheel. It all depends on where you need the wheel to sit in the opening.
For example: using an 18x8 wheel with the mounting surface right in the center of the wheel
The wheel would have a backspace of 4", and an offset of (0)
Now move the mounting surface out 50mm (approx 2") towards the outside of the vehicle
The 18x8 wheel would now have backspacing of 6" or an offset of 50mm (Mounting surface is 6" from back edge of wheel, and 2" from centerline of wheel)
Offset is just as variable as backspacing. That's why you see some wheels offered in many different offsets for the same width wheel. It all depends on where you need the wheel to sit in the opening.
#27
08-23-2007 | 09:54 PM
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Joined: Oct 2006
Posts: 1,460
RE: Another Rim/wheel question..SORRY!
alright, i got a PM back from the guy.
he said if i go with a 18x8 rim, the widest tires i can go are 215/40/18. however, the tires will be stretched...
like this.....
he said he ran with 225's once, and he rubbed. not alot, but he still rubbed....
i tihnk i might head out rim shopping on my next day off and find myself some 18x7.5 rims......
he said if i go with a 18x8 rim, the widest tires i can go are 215/40/18. however, the tires will be stretched...
like this.....
he said he ran with 225's once, and he rubbed. not alot, but he still rubbed....
i tihnk i might head out rim shopping on my next day off and find myself some 18x7.5 rims......
#29
08-23-2007 | 11:41 PM
Senior Member
Joined: Oct 2006
Posts: 1,460
RE: Another Rim/wheel question..SORRY!
ugh.
so ive started browsing thru car magazines again....
i forgot how stressful wheel shopping is.....
even if i find a set of rims i love, i still have to make sure they come in 18x7.5, with a 45 offset, with a 5x114.3 bolt pattern.....
im trying to find a set of black or gunmetal 5 spoke rims, with just the outer part of the lip polished, (like the tenzo rims) and im having no luck wat so ever.....
so ive started browsing thru car magazines again....
i forgot how stressful wheel shopping is.....
even if i find a set of rims i love, i still have to make sure they come in 18x7.5, with a 45 offset, with a 5x114.3 bolt pattern.....
im trying to find a set of black or gunmetal 5 spoke rims, with just the outer part of the lip polished, (like the tenzo rims) and im having no luck wat so ever.....
#30
08-25-2007 | 12:58 PM
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Joined: Mar 2007
Posts: 8,666
From: Manor, TX (Outside of Austin)
RE: Another Rim/wheel question..SORRY!
ORIGINAL: sstlaure
I think that's smart....tires stretched over the rim just make it look like you ran out of money and couldn't get tires that fit your rims properly.
I think that's smart....tires stretched over the rim just make it look like you ran out of money and couldn't get tires that fit your rims properly.
And wheel shopping is never easy, but when you've got a Mazda3 (a fairly limited selection indeed) it's even harder.