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I'm quite the noobie when it comes to things related to tires and wheels so any advice would be appreciated. I drive a 2004 xt and have found a set of 17x7.5 wheels with a +38 offset and a 5x100 bolt pattern wrapped in 205 40R17 tires. The million dollar question is whether they will work on my car. Any advice is good advice at this point. Thanks much.
 

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The Modfather
2019 Impreza 5dr Sport - Manual
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OEM offset is +48, 38 sounds like you will have issues.
 

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not to hijack your thread, but to hopefully spread the knowledge of offset cause i'm not sure either...

if stock is +48, and he's trying to fit +38, is +38 going to push the wheels 10mm outward or inward
 

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Outward towards the fender. My guesse is 38 will make it rub. You might be able to get away with it if you roll the fender.

Bland...
 

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2004 Forester XT Premium 4EAT
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Even if you can make it fit, it will still put undue stress on the wheel bearings in the long run...
 

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'09 STI
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I have 7.5" in +48 and it looks like there is plenty of room to go 10MM out. Though like eveyone else is saying, it's not optimum. I would only run this little positive offset if I was trying to stuff super wide tires on for track use.
 

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The Modfather
2019 Impreza 5dr Sport - Manual
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Don't forget about the change in Scrub Radius, might make it handle funky.

http://autorepair.about.com/library/glossary/bldef-725a.htm

SCRUB RADIUS
Definition: The distance between the extended centerline of the steering axis and the centerline of the tire where the tread contacts the road. If the steering centerline is inboard of the tire centerline, the scrub radius is positive. If the steering centerline is outboard of the tire centerline, the scrub radius is negative. Rear-wheel drive cars and trucks generally have a positive scrub radius while FWD cars usually have zero or a negative scrub radius because they have a higher SAI angle. Using wheels with different offset than stock can alter the scrub radius.

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http://www.ingallseng.com/terms.htm#Scrub%20Radius
Scrub Radius

Scrub Radius Definition

Scrub radius is the distance at the road surface between the tire line and the SAI line extended downward through the steering axis. The line through the steering axis creates a pivot point around which the tire turns. If these lines intersect at the road surface, a zero scrub radius would be present. When the intersection is below the surface of the road, this is positive scrub radius. Conversely, when the lines intersect above the road, negative scrub radius is present. The point where the steering axis (sai) line contacts the road is the fulcrum pivot point on which the tire is turned.

Squirm

Squirm occurs when the scrub radius is at zero. When the pivot point is in the exact center of the tire footprint, this causes scrubbing action in opposite directions when the wheels are turned. Tire wear and some instability in corners is the result.

Applications in Suspensions

MacPherson strut equipped vehicles usually have a negative scrub radius. Even though scrub radius in itself is not directly adjustable, it will be changed if the upper steering axis point or spindle angle is changed when adjusting camber. This is the case on a MacPherson strut which has the camber adjustment at the steering knuckle. Because camber is usually kept within 1/4° side to side, the resulting scrub radius difference is negligible. Negative scrub radius decreases torque steer and improves stability in the event of brake failure. SLA suspensions usually have a positive scrub radius. With this suspension, the scrub radius is not adjustable. The greater the scrub radius (positive or negative), the greater the steering effort and the more road shock and pivot binding that takes place. When the vehicle has been modified with offset wheels, larger tires, height adjustments and side to side camber differences, the scrub radius will be changed and the handling and stability of the vehicle will be affected.
 

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re:eek:ffset

hi. im planning to buy a mags that is 17" pcd 100 for my subaru forester.. it says that the offset is 45. would it fit my ride or there will be any other issues with it? thank you.
hope to hear from you guys..thanks
 

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you guys are making this harder than it is. I suck at/hate math and I have no problems figuring out which combos will fit my vehicles/customers vehicles.

a) there are TONS of awesome "will it fit" calculators out there. As long as you know the stock tire/wheel size and offset from your car, the rest is gravy.

b) if you want a general idea of what will fit, just do some really simple math and take a look at how things sit now. Finn, if your stock wheel is 6.5" wide and a 48mm offset:
you can subtract the stock rim width from the new rim width and divide it in half - in this case the added wheel width will move the rim .5" inches closer to the fender lip. Do the same for the offset - 48mm-38mm for another 10mm closer to the fender lip, or another .39". Measure out .89" from the tire/wheel edge of your existing setup, and you can ballpark whether it will work or not.

Of course there are many other factors (camber, drop, tire brand and width, etc.), but that should get you started.
 

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2007 Forester Sports XT 4EAT
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To better understand wheel measurements and dimensions I present:
I go here to check out my wheels. Wheel / tire size calculator / comparer - RIMS-N-TIRES You can dial in the offset & see what the offset does as the image is redrawn.

BTW, I'm running Toyo Proxes 4, 235/50-17 on Motegi MR7 wheels with a +40 offset. My winter wheels are Nokian Hakkapeliitta 4, 215/60-16 on Motegi MR7 wheels with a +42 offset (my old summer wheels). I have not had any problems running these wheels.

Bobby...
 
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