Are 17"x8" rims with 48mm offset the answer for me?

[rednofive]

Just bought my MS3 last week!
I see that it comes with tires that are good for about 20K miles, if I’m lucky with my commute and fun with turning circles and off-ramps.

I wanna keep the stock rims and Potenza’s for DS-ST autocross with the SCCA.

I’ve never bought aftermarket wheels/tires other than what Tirerack (or equiv) web-site lists.
I thought I’d play around a bit. I’ve read through most of this forum’s wheels/tires threads…
Can someone check my thinking/facts?

For daily driving, I’m looking for:
• No need to roll fenders and I don’t wanna worry about suspension contact with tire width
• Wheels that will comfortably support 225mm width tires (8” rims?) and therefore no problematic squirm from sidewalls
• Better resistance to bending (17” tires will give a bit more margin from the rim when maintaining a correct wheel/tire diameter like stock)
• 17”x8” rims will likely be slightly lighter than the 24 lb 18”x7” stock rims
• New Tires + wheels weighing less than the 48 lbs of Stock tires/wheels
• Tires that are good for the four seasons of Indiana and can some pot-holes

I used this link:
http://www.wheelsmaster.com/rt_specs.jsp

with this input for the wheel/tire on the left:
215, 45, 18, 18, 7, 53

And this input for the wheel/tire on the right:
225, 50, 17, 17, 8, 48

Looks darn close and it SAYS the offset would be OK, but then again, the drawing doesn’t know jack crap about whether or not +10 on the fender side is OK versus being +10 on the suspension side…

I’m thinking about finding some 5-114mm bolt-pattern 17”x8” rims with 48mm offset that weigh <24 lbs.
I’d get all-season tires with a treadlife warranty > 40K miles and wheels + tires weight < 48 lbs.
Got my eyes on 225/50R17 Yoko Avid V4S at 27 lbs each
http://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=AVID+V4S&vehicleSearch=false&partnum=25VR7V4S&fromCompare1=yes&speed_rating=U&speed_rating=H&speed_rating=V&speed_rating=Z&speed_rating=W

Can someone check my thinking on all this?
Do I have my facts straight about the stock tires and wheels size, weight, offset?

Thx.

[coololddude]

bigwheels.net lists offset range from 42 to 50 and wheel size range from 18X7.0 to 20 X 8.0 for the MS3 .check um out

[SuperStretch18]

...Looks darn close and it SAYS the offset would be OK, but then again, the drawing doesn’t know jack crap about whether or not +10 on the fender side is OK versus being +10 on the suspension side…


+10 means that the hub is offset 10 mm forward from the center of the wheel (rim extends further towards the suspension). -10 would be offset 10 mm backward from the center and the rim would extend towards the fender...

I used that site to pick my wheels and it was pretty spot on...

[hard2kill]

bigwheels.net lists offset range from 42 to 50 and wheel size range from 18X7.0 to 20 X 8.0 for the MS3 .check um out

I just checked their site and it seems like they only carry wheels that are straight up baller or one's I've never heard of before. I don't know how much stock I would put into that site for reference.. Just .02

[Young Roids]

You say you don't want to go too wide on an 8 inch rim for fear of sidewll squirm bu then you want to go 17 inch and make your sidewall higher, that's gonna cause more squirm than going a little wider. I think you could run up to a 245 on an 8 inch rims without sidewall squirm issues.

[rednofive]

You say you don't want to go too wide on an 8 inch rim for fear of sidewll squirm bu then you want to go 17 inch and make your sidewall higher, that's gonna cause more squirm than going a little wider. I think you could run up to a 245 on an 8 inch rims without sidewall squirm issues.

I agree that going a bit taller on the side wall will make it a bit less precise, but putting a 9.6" tire patch on an 8" rim is typically at/beyond most tire manufacturers suggestions (they usually using a 1.5" range of wheels to match the tire to)...

Also, based on all the threads I read, it doesn't sound like 245's will fit without rubbing. I saw a lot of people comfortable with 235's, but not 245's. I could be wrong...

[rednofive]

+10 means that the hub is offset 10 mm forward from the center of the wheel (rim extends further towards the suspension). -10 would be offset 10 mm backward from the center and the rim would extend towards the fender...

I used that site to pick my wheels and it was pretty spot on...

Did you mean to say it the other way around?
If the offset is a positive number to the left of the center line in the drawing and the left side of the drawing is the outside of the wheel, then +10 means 10 more than the positive number you already have, which means more towards the fender. And vice versa on -10.
Just playing with the offset pull-down bar suggests that, too...
start with 10 then pick 20, it goes more left (more positive). then pick 30, even more positive (out towards the fender).

Either way, you've used the site.

So did you just move the offset around and look at the comments to see what they said? I originally used 40 mm for offset, but that stated that 40 would be a problem on most cars.

[SuperStretch18]

Did you mean to say it the other way around?
If the offset is a positive number to the left of the center line in the drawing and the left side of the drawing is the outside of the wheel, then +10 means 10 more than the positive number you already have, which means more towards the fender. And vice versa on -10.
Just playing with the offset pull-down bar suggests that, too...
start with 10 then pick 20, it goes more left (more positive). then pick 30, even more positive (out towards the fender).

Either way, you've used the site.

So did you just move the offset around and look at the comments to see what they said? I originally used 40 mm for offset, but that stated that 40 would be a problem on most cars.

As you said, the left side of the image is the outside of the fender. The greater the positive offset, the closer to the outside rim (left) the spokes are, but the wheel itself would mount closer to the suspension (right). With a negative offset, spokes are closer to the inside rim, but the wheel itself may extend from the fender. I know I'm probably not explaining that well.

I had an idea of what clearance I had on my car, so I just looked for those numbers when I was "sampling" each wheel. The option I came up extended 1/2" further out of the wheelwell and 2/5" closer to the suspension, but worked perfect! If it says that it might be a problem, I would just check your clearances on the stock tires, but they are probably right...

[rednofive]

As you said, the left side of the image is the outside of the fender. The greater the positive offset, the closer to the outside rim (left) the spokes are, but the wheel itself would mount closer to the suspension (right). With a negative offset, spokes are closer to the inside rim, but the wheel itself may extend from the fender. I know I'm probably not explaining that well.

I think I understand the way you're looking at it.
You're describing much of what I found here:
http://en.wikipedia.org/wiki/Offset_%28wheel%29

In the end, I need to do the math that considers the offset of the hub mounting surface relative to the centerline and the width of the tire surface relative to that centerline, the fender, and the suspension and the scrub radius. Not easy to measure out, but I get it.

thx.

[Kurt07]

I have 17X8 with a 50mm offset with 235/45-17 tires. There is no fitment issues whatsoever.

[rednofive]

I have 17X8 with a 50mm offset with 235/45-17 tires. There is no fitment issues whatsoever.

Kurt07 - thanks for the data point. I'll check out my tire options on that size.