Forester STI – Rota Grid Drift Wheels

The wheels that were on the Forester when I bought it are proper GC-010E Prodrive/Bridgestone branded forged items made in the Rays factory in Japan. They’re quite a desirable wheel, look good and are about as light as a set of 18’s are going to get so they drive very well.

Me being me though, I fancied something different and always loved the Grid Drifts I had on my Evo VI. They were pretty much flush with the wings and with a bit of stretch on the tyres. They really helped fill the arches and add to the aggressive look. A couple of pictures of the Evo…



Oh I want an Evo again!

Anyhow I have a Forester STI and I thought it could do with some wider wheels or at least something with some more offset than the 17 x 7.5 ET 47 wheels on it. I wasn’t in a rush to get some and neither did I really want to spend the kinda money they are new with tyres so I just kept regularly checking eBay, Facebook marketplace, Gumtree etc for something with the right PCD, around the right width and offset.

After months of regularly looking a used set came up for sale at a price I couldn’t refuse and they were about a 1 1/2 hour drive away from me meaning I could fetch them myself and see them in person before handing over any cash. I agreed with the seller to meet him on a Saturday morning so Jem and I drove up early to take a look and hopefully come home with them which we did.

Another reminder of why I got a Forester to replace the Evo, fitting these in the back of the Evo would have been a real pain if not impossible.



I gave them a good wash, not that they were particularly grubby, let them dry then stacked them up ready for when I would get a chance to trial fit them.



The specs of the wheels and tyres:

Size: 18 x 9

PCD: 5 x 100

Offset: ET38

Tyres: 235/40 ZR 18


They came with nearly new Michelin Pilot Sport tyres too as they had been previously fitted to a WRX hatch but not for long.

They are on the wider end of the sizes I was looking for so I had no idea if they would clear the OEM STI dampers plus I had a suspicion they would not clear the front Brembo calipers without some spacers. But I got them at a price that meant I could take a chance on them and if they were just too wide I would certainly be able to sell them on and get the same money back for them.

A comparison of the two wheel and tyre combinations.


Only one way to find out if this extra width and offset would fit, get the car in the garage, up on the lift and give the wheels a try.



Well, as expected, they didn’t clear the STI Brembo caliper on the front. I have a selection of spacers so tried 3mm first but that wasn’t quite enough. A 5mm spacer meant the wheel cleared the caliper but I think that’s about on the limit with the standard length studs, certainly without some hubcentric spacers with the correct extended spigot rings.



Clearance to the caliper with the 5mm spacer.


Not a lot!


So I found some 5mm hubcentric spacers with the right size spigot rings on eBay.


The spigot rings need an inner diameter of 56.1mm to fit the Subaru hub and an outer diameter of 73.1mm to fit the Rota wheel.


Quick check that the spigot ring fits the hub…


…and wheel.



Wheel on, this will be ok to drive with the standard length studs to check there’s no other problems with things touching or rubbing in places they shouldn’t. If there are no other problems and I decide to keep the wheels I will fit longer studs.


Now the rear wheels. Obviously the calipers weren’t going to be a problem here but the rear arch isn’t as wide as the front and inner edge of the wheel sits closer to the damper body so there could still be problems.


The wheel fits with no spacer but the inner rim was very close to the damper body. The only way I could prove there was a gap was to cut a piece of plastic to use as a kind of feeler gauge.





The other side. You can just see light through the gap.


In theory, as the the hub is solidly mounted to the damper, there shouldn’t be movement for the wheel rim to get any closer to the damper but I know that in reality there’s always a little movement in suspension like this especially when you start to load it up.

So if I fitted the rear wheels with no spacer to test and they rubbed badly then clearly I’d hear it. But if they only touched occasionally or not bad enough that they made a very noticeable noise then they could rub and cause damage before I would notice. The best way I could come up with to test if there was much movement or enough that the wheel rim could occasionally rub on the damper was to paint a few dabs of white paint on the inner wheel rim and monitor it. The paint would certainly get worn of pretty quick if there was regular contact between the wheel and damper.




Both sides done as there will always be slight differences from one side to the other so you can’t rely on both sides being OK if one is.

With all four wheels on with no apparent clearance issues I could get the Forester back down on the ground and see how it sat on them.


A Fair bit of poke, maybe a little more than I’d choose but not too silly.



I took it for a short drive listening out for any rubbing noises but heard nothing which was a good start.

A few pictures of how it sat, still on the OEM Forester STI springs and dampers.







Not too bad but if the wheels were going to stay then the ride height would have to be reduced and with the 5mm spacers on the front I was going to want to fit some longer studs.

I decided to run on the wheels like this for a few weeks to keep an eye and ear out for any rubbing and see how I liked the look.

After a little while it was clear the inner rear wheel rim was occasionally rubbing on the damper body so I’d either need to fit some 2-3mm spacers just to give a little extra clearance or maybe some coilovers would give a little more clearance than the OEM STI inverted damper does?

Either way I was pretty happy with the wheels but I wasn’t going to leave them on the car as it was. I wanted to fit some longer studs on the front and lower the ride height either with some different springs or a set of coilovers.

So I refitted the other wheels, got a wheel storage rack and stuck the Rotas on it for another time.


I had a fairly big job to do on Jem’s Mini over winter so the Forester would have to wait.