paulhoubart

Gidday,

Scooby Newbie here, just purchased a MY94 WRX STI, jap import. Got a HKS exhaust, standard otherwise. Given that this is the 5 door / estate version, and that I've got the poxy standard 15 inch wheels, my question is .....

What is the biggest wheel / tyre combination I can go for, given that the car will probably have some fairly heavy loads ( wine from trips to Europe, etc.) in the back sometimes, and the last thing I want to do is have the back wheels catching. Any opinions on this ?

P.S. Why are the brakes so bad on this car, as well ?

GREEN SCOOBY

Exactly the same as the jap/uk saloons/coupes
(exept 22b).Mine has 17 inch chronos and 205/45/17 rubber(prodrive wheel and correct sizes)and i know of some one with 18's and if not mistaking 40 profile rubber.

NITO

Hi Paul,

I use Compomotive 18"x7.5" Split rims ET50 with Pirelli P7000 215/35/18 tyres. This is the biggest you can really get away with without needing any mods. The P1 uses 225/35/18 but I think they needed slight modding to the rear arches to fit this (I'm not sure on this though sinvce they also have a higher than 50 offset 52/53) They never ever catch and the car is lowered etc. You'll be fine with either 7x18 or 7.5x18 as long as the offset is 50+. Any lower offset and you will get scrubbing on the rear arches.

Nito

paulhoubart

Thanks for the help, guys. Much appreciated.

Nito, as far as 18 inch wheels are concerned, are you sure they will never catch ? Not that I doubt you, but I don't want to have to explain to the missus after we've loaded the car up with luggage, shopping, more shopping and the dog etc etc why the car won't move because the wheels are too big !

NITO

Absolutely positive.
As long as you stick to 50 offset and Pirelli P7000 215/35/18. With regards to other 18" fitments I can't say. An 8" width is too wide so 7 or 7.5" and 50 offset!!!

Nito

simes

Not that I really know anything about this but I think as Nito has hinted, the offset, i.e. in his case ET50, is the key to whether the wheel will fit, not necessarily the size of the rim itself.

I believe the absolute farthest you can go on a scoob is ET48, but having said that my 17 inch wheels are ET50 and are quite close to the bodywork, so it might be starting to get close.

What I don't know is the relationship between offset and width, as I said, I'm not really an expert in this area to say the least, but obviously 18 inch wheels with ET50 offset fit as per Nito's wheels.

What you might want to consider though is whether you might want to upgrade your brakes later, and whether the upgrade would fit with the wheels, which from your comment seems likely (the answer to your question BTW is they just are).

For example, my SS Brembos were very tight under my MY99 wheels (16inch, offset = ET52?), but have literally inches of clearance with my 17 inch set, offset ET50.

I know there are some 17 inch wheels around that would not fit such an upgrade.

If anyone can explain offset vs rim widths etc I'd be interested to learn more.

Hope this helps.

Cheers

Simon

Hoppy

Hi Paul. What do you mean by bigger wheels? You can fit anything from 15in to 18in wheels on a Scoob, provided the offset is within 50-53mm. But the overall diameter of the wheel/tyre remains the same (as it must do to a) fit the car, and b) keep your speedo accurate) by altering the aspect ratio to a lower profile. eg 205/50x16 is the same diameter as 205/45x17 or 215/40x17.

If you mean wider wheels, I wouldn't go there. Standard width is 7in. Some say 7.5in fits but this is uncharted territory.

But from what you've said, this is what I'd do. Upgrade to 205/50x16 tyres and 16x7in wheels. This is standard Scooby kit and there are plenty advertised in the Private - For Sale section. I suggest this as, when you've got the car fully loaded, the higher profile tyre will run smoother and be less prone to damage. I speak from experience here as last week I hit a piece of wood and wrecked a 215/40x17 tyre and wheel - £300!!! With the extra height of the side wall in a 205/50x16 tyre I might have got away with it.

Secondly, you're right about the brakes. And again given the loads you'll be carrying, best get them upgraded too. With the 16in wheel you can get the newer 4-pot calipers fitted (again, look in the for sale section). Fit them with an upgraded Group N disc and better pads. Finally, you might want to improve the rear brakes, too, to the newer ventilated disc. I believe these fit straight on, but best check first.

Richard Hopkins

Hoppy

Simon, offset and stuff. This confuses lots of people, including me, but it's really very simple.

The width of the wheel is the width! ie 7in for an Impreza. The ET or offset is the distance from the centre of the rim (3.5in) to the mounting face of the wheel. If the mounting face and the centre were both plumb in line, the offset would be zero.

But it never is, and all cars have some offset. Imprezas have more than most and a lot of wheels won't fit, which is why there are contstant posts on here about which wheels will fit and which ones won't. The thing to remember is that the LOWER the offset, the more the wheel sticks OUT.

The Subaru standard wheel has a 53mm offset, that is to say the mounting face is 53mm nearer the spokes, measured from the centre line.

Prodrive recommend 52mm as being the optimum from a performance perspective, and 50mm is - in my experience - the lowest you can go before hitting clearance problems and also beginning to upset the handling. Some say 48mm is okay, but you might have to remove the plastic trim inside the rear arches to do it. It's that close! There are lots of wheels available in 48mm offset, hence the debate.

The difficulty with fitting upgraded brakes - Brembo, AP Racing, Prodrive etc - is an entirely different issue. It's especially difficult as no wheel manufacturer quotes the measurements you need to know, and that is the space between the outside face of the caliper and the inside edge of the wheel spokes.

Wheels of identical size and ET can vary dramatically here and the only 100% reliable way is to literally fit the wheel to the car and see if it still turns! Not very convenient, but is another good reason for going on a track day as you'll find loads of cars there with different wheel and brake combinations. If you pick your moment, most drivers would be happy to take a wheel off and put your wheel on, to see if it goes.

A much easier way is to choose an AP Racing brake upgrade and use their fitting guide. It's nothing more than a sheet of A4 paper which you cut around the dotted line. With your wheel flat on the floor, hold the paper vertically and locate it in the wheel centre hole. If the edge of the paper clears the inside face of the spokes, you're okay.

It sounds a bit crude, but I've done it and it works very accurately. For example, I'm after the 6-pot AP Racing brake upgrade. This is a comfortable fit with my Radius R3 17x7 wheels, but is so tight with Speedline ST2 wheels that I'm going to have to do a physical check with someone friendly at Donington tomorrow. At the other extreme my new Motorsport Revolution RZX wheels (from Scoobysport) have enough clearance to fit a small bungalow in there!

Sorry to ramble. Hope this helps.

Richard Hopkins

Gary Foster

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Hoppy:
<B>Finally, you might want to improve the rear brakes, too, to the newer ventilated disc. I believe these fit straight on, but best check first.
[/quote]

Just did this myself on an MY97. As hoppy says, 4 Pots (From STI / P1 / MY99-&gt; ) fit straight on (with the new disks of course as they are bigger). The rears are the same story, if you want the vented disks you'll also need the MY99 calipers to fit the disks (wider), but they bolt straight on. Scoobysport did a second hand pair of MY99 rear callipers for me for £100.

Gary

paulhoubart

Hi Guys,

Thanks for the feedback on the wheel/tyres combination - for the moment, I'm going to stick to the 15 inch wheels. I had 4 people in the car over the weekend, and I managed to ground something out. Only happened the once, and I suspect the HKS exhaust is sitting quite low, but until I figure out wether it's been lowered, and how much, I'll leave the tyres as is !

As far as brakes are concerned, 4 pots sound the way to go. Has anyone on the BBS had any dealing with ABP, near Crewe ? They're pretty near to me, and they advertise as doing alot of Subaru work. I'll either get them to do the work for me, or DP Motorsports. Any feedback / comments on these companies would be welcome.

Cheers !

Hoppy

Simon, I think I know where you're coming from with the lower offset means more brake clearance, but it just isn't true in practise.

Here's another unreliable guide as to which wheels might clear! Look at the wheel square to the width. Do the spokes stick out further than the rim? ie is the total width of the wheel more than 7in?

This is hardly an infalible test, but it's true of the three sets of wheels I've got where the outer edge of the spokes is at least 1cm proud of the rim.

Richard Hopkins

simes

Richard/Hoppy

Thanks for the info, which I read and drew a little piccy and now understand it I think!

I appreciate what you're saying about individual wheel designs and brake upgrades, but I guess lower offsets will in general stand a better chance of fitting?

Cheers

Simon