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Does anyone know what the stock offset (ET) of the Legacy Turbo five spoke alloy wheels is? Is it 53 mm the same as the third-gen snowflake wheels?

Thanks,

Bez

Just out of curiosity, is there a particular reason you're concerned with the offset?

I think stock subaru wheels range anywhere from +55 to +48. As long as you're in that range, you're safe. I'd be willing to run as low as +45 before I thought my wheel bearings would suffer.

If you run any stock 5x100 subaru wheel on your car, you won't have fitment issues.

Probably because I am a mechanical engineer and prefer to have the correct offset on the rim as it does affect the design bearing loads. A 55 mm ET on a car designed for a 48mm offset (i.e. Forester) even thought it is only 7 mm, changes the ET by 15% from the original design spec.

We have two Legacys, a Forester and an Impreza in our Subaru fleet and I never swap wheels between cars.

Bez

Bez wrote:Probably because I am a mechanical engineer and prefer to have the correct offset on the rim as it does affect the design bearing loads. A 55 mm ET on a car designed for a 48mm offset (i.e. Forester) even thought it is only 7 mm, changes the ET by 15% from the original design spec.

We have two Legacys, a Forester and an Impreza in our Subaru fleet and I never swap wheels between cars.

Bez

Except that, the bearing spec is the same for like 15 years or more, the hubs and knuckles are direct replacements for like 15 years or more, and people have been swapping OEM 5x100 wheels for like 15 years or more and wheel bearing issues are not a chronic problem.

On my turbo Legacy 5-spoke wheels, the stock offset is 56 MM.

Surprised that the ET is so high at 56 mm. Thanks for taking the trouble to check for me since I am going to be auto-crossing the car and I don't want to change the offset of the wheels.

Bez

Bez wrote:Probably because I am a mechanical engineer and prefer to have the correct offset on the rim as it does affect the design bearing loads. A 55 mm ET on a car designed for a 48mm offset (i.e. Forester) even thought it is only 7 mm, changes the ET by 15% from the original design spec.

We have two Legacys, a Forester and an Impreza in our Subaru fleet and I never swap wheels between cars.

Bez

It doesn't really matter that much.

Plus offset will vary depending on rim/wheel size & width. So you can't just look at the original offset and make a blanket statement that's what you have to run.

everything non-forester/outback/baja is either +53 or +55.
6.5" or narrower wheels are +55
7" and wider wheels are +53.
The one exception is the 08 sti, which is +55.

The tall cars have less offset (+48) because they use bigger tires. I think the added scrub radius (and bearing load) from dropping the offset down to from +55 to +48 would be greater on a forester than an impreza because of the taller strut and lower SAI. And guess what, foresters come with +48 wheels and they use the same bearings/uprights/control arms as imprezas. Going from a +48 to a +55 would reduce the scrub radius and bearing load.

If we were talking about putting +35 wheels on the car, then yes, I would be concerned about the wheel bearings and the funky steering issues that arise.

the stock wheel is 15 x 6 with a 55mm offset. it comes with a 195/60/15 or 195/55/15 tire.

as for right now, i'm running 17" 225 45 on a 7" rim with a 42 mm offset. so far so good, it's been about 3 months. i did have to roll my rear fenders.

jamal wrote:everything non-forester/outback/baja is either +53 or +55.
6.5" or narrower wheels are +55
7" and wider wheels are +53.
The one exception is the 08 sti, which is +55.

The tall cars have less offset (+48) because they use bigger tires. I think the added scrub radius (and bearing load) from dropping the offset down to from +55 to +48 would be greater on a forester than an impreza because of the taller strut and lower SAI. And guess what, foresters come with +48 wheels and they use the same bearings/uprights/control arms as imprezas. Going from a +48 to a +55 would reduce the scrub radius and bearing load.

If we were talking about putting +35 wheels on the car, then yes, I would be concerned about the wheel bearings and the funky steering issues that arise.

I am looking at these 16x8 ESMs but the tallest offset they are available in is +35. I'm hoping Jamal and others can elaborate on the bearing and steering issues expected.


Wheel bearings: As I understand it, the further away the wheel protrudes from the hub, the greater leverage effect that will put higher load and stress on the bearing, thus wearing it out more quickly?

Steering issues: What could be expected?

Besides any bearing issues that may arise (which I don't think you'll have any....they may wear quicker....but I don't think it would be exponentially quicker) I think you'll run into fitment/rubbing issues in the rear. The 93 may more room in the rear than my 90, but when I was looking at tires back in 96 a 15" wheel with +35mm offset rubbed in the back.

Thanks Josh, I assume you had problems clearing the suspension because of the positive offset.

I might be able to test fit a friend's different set with the same dimensions.

What happens is that the wheel and tire has more leverage over the steering rack, so you get a lot more feedback and steering can be harder. This also means that bumps are more likely to jerk the wheel and upset the car, and 20mm isn't an insignificant amount.

Ideally the tire will pivot at or near the center of the tread, which is called zero scrub, but obviously if you want wider wheels and tires you can't do that without changing the suspension geometry because the tire would hit the strut. If you wanted to reduce scrub for a given wheel/tire, you could install wider control arms and/or add camber at the strut top (however, increasing SAI comes with a new set of issues).

Doing the math on that wheel puts the inside of the rim about 11mm closer to the strut and 40mm farther out, and if you have a 225mm tire it will be 5mm farther from the strut and a whole inch closer to the fender compared to a 195 (although most tires measure differently from the printed size). A 235 on that rim would put the inside of the tire exactly where they are now.

So anyway, I would look for a slightly higher offset as possible in the +45 range. You should be able to get an 8" wide, +45 wheel in there with 225s and have room to spare at the strut, although it depends on your struts. 205s on a +55 fit fine on my stock 93 suspension. 225s on a +53 fit on my stock 98. Currently have 225s on +55 wheels with camber bolts and slotted front struts to angle the top of the tire even closer to the strut, but the struts are from an STi give more clearance.

Bearings don't really worry me that much anymore and I used to be all against low offsets because I thought it was a problem. When you are cornering hard, which places more load on the bearing than just driving down the road, a lower offset will actually reduce the forces it sees.

Dynamic Entry wrote:Thanks Josh, I assume you had problems clearing the suspension because of the positive offset.

I might be able to test fit a friend's different set with the same dimensions.

No, I had rubbing issues on the inner fender liner. A smaller positive offset will move the wheel outwards. A larger positive offset will suck the wheel inwards towards the strut.