sti_jdm

Hi im new to this forum, i recently bought a 54 plate GDB JDM STI. Two of the alloys were curbed so i thought id buy some replacements however i noticed that the UK spec STI has 225/45/17 fitment whereas my jap spec ones are 235/45/17?!
If i buy some UK STI alloys with 225/45/17 will they be ok? Or i noticed that on the new 2008 WRX they have the same alloy in silver but the fitment seems to be 235/45/17.
Will either of these options be ok?
Thanks in advance

richiewong

225/45/17 will be OK or you could go for some 18's with 225/40/18.

18's will fill the arches and look much better

Chelspeed

The PCD changed for the 2005 STi. With a 54 plate import could be one or the other so take care when buying wheels.

The most obvious change is the plastic rear wheel arch extensions on the 2005 model for the wider track. Does your's have these or not? If so then you have the later 5 x 114.3mm pcd and wheels off a 2004 and earlier STi won't fit. If no wheel arch extensions then you have the earlier 5 x 100mm pcd and wheels off a 2005 and later STi won't fit.

If in doubt measure the pcd or try the wheels over the studs before yoiu buy them.

When mixing tyres on the car it's not the width that matters it's the circumference as that affects the gearing (wheel revs per metre). Get that too different front to rear and the centre diff is forever fighting the wheels. If both are 45/17 then the circumference of a 225 width will be 98.6% of the 235 width. I'd guess you'd get away with that as it's only the same as having new tyres on the rear and worn ones on the front and no-one worries about that. The big difference would come if it was 235/40/17 against 225/45/17 or similar.

SamUK

iTrader: (1)

Will a 235/40/18 fit...or would it rub?

--Sam

sti_jdm

Hmm im not really bothered too much about the looks, id rather keep them standard as 18s will only be heavier....

I had a look and my car seems to have the wheel arch extensions but i heard that the JDM STI's come with them as standard. To be sure does anyone know how to measure the PCD of my wheels?

SamUK

iTrader: (1)

but 18's will handle better..i think they recommend 18's once your ppp'd your car...300bhp upwards...


though i dnt think the 18's weight will make any noticable difference...you could spend near £1000 and get original alloys...which will be light...

Chelspeed

> To be sure does anyone know how to measure the PCD of my wheels?

It's just the diameter of the circle that goes through the centre of all the wheel studs.

If there were four studs then the pcd is just the distance between the centre of two opposite studs.

With five studs it's a little bit harder. You need to measure from the centre of one stud to where the circle would be half way between the two studs opposite. Probably difficult to get +/-1mm as you're guessing where the circle would be but you don't need to be that accurate as the only choices are 100mm or 114mm. You should be able to measure this difference pretty easily.

As an alternative what about the length between two studs? If I hadn't stopped doing trig 30 years ago I could probably work out the length between two studs for each pcd. It's the chord of a segment which subtends 72 degs..... Eh hang on it's just a triangle, simple sin rule. Calculator to the ready.

So it's easy. Just measure between two studs next to each other, if they're 59mm apart then it's 100mm pcd, if they're 67mm apart then it's 114.3mm pcd.

Edited because pcd is diameter not radius......

dunx

iTrader: (3)

My much larger alloys are lighter than std ones....

DunxC