ace1981

This is one for the tyre / wheel experts.

I currently have a set of 17" Prodrive alloys on my car, with 205/45/17 tyres on (see attachment).

I'm looking for a spare alloy (or possibly two), and have come across this on the 'Bay:-

http://www.ebay.co.uk/itm/Genuine-Pr...item3f2cb5b735

Clearly the same alloy as mine, but with 225/45/17 tyres on them.

Question is this: I know the first number of a tyre measurement is the width, but is it actually possible that different width tyres can fit the same alloy? I'd have thought the tyre width needed to match the alloy width.

I understand that the tyre height is a percentage of the width, and therefore it changes proportionately with the width itself - and for that reason, all four corners need to be the same size tyre. I just don't see how a tyre 2cm wider than mine can fit correctly onto the same alloy.

I have four good 205/45/17 tyres on my Prodrives, all less than a year old - so the plan would be to get the replacement alloy, and then transfer the 205 onto it, rather than buy 3 new 225s.

Thoughts?

alcazar

iTrader: (2)

It all depends on what car you have them fitted to. You don't say what yours is, so I'll assume from the tyre size that it's a classic?

The accepted correct size for classic on 17" wheels is 215/40 17". This gives the rolling radius as near as possible to the original, with the speedo reading SLIGHTLY over, which is what you want if it's not spot on. It also stops the tyres rubbing on the suspension, or bodywork, without having to go to rolling the arches etc.

On newer cars, Subaru altered the suspension and bodywork, and 225/40 17" became the OE size.

Sizes BIGGER than 215/40 will rub on yours, sizes SMALLER will work but give a harsher ride.

HTH.

bustaMOVEs

iTrader: (31)

40 is not the oe size on new ages on 17s it's 45, classis and new ages is all the difference in width,
New age sti 225
New age wrx 215
Classic 205

WRXrowdy

iTrader: (2)

It is not strictly critical that only one size tyre will fit a certain width rim, although personally I would only go + - one size, but if you check out old VW scene many people put way too small a tyre on big rims to give the tyre wall a stretched look.

Put your 205 on the spare wheel, and put the 225 on ebay if its any good.

ace1981

It is jndeed a classic, Alcazar.

The only reason I'm really asking is that if it's just a case of buying the alloy, removing the 225 and replacing with the 205 currently on mine, it's worthwhile

Otherwise it seems to be buy a new set of alloys complete with tyres - which I would rather not do if buying a single alloy and replacing the tyre is the sensible answer.

ace1981

By that, I take it that it is indeed possible to fit 205 or 215 width tyres on the alloys then?

I'm not an expert at all, but I would have thought the required tyre wdith was dictated by the width of the alloy.

JohnD

iTrader: (5)

The 225/45 will have a larger rolling radius than the 205/45 (9mm higher sidewall so 18mm larger in diameter) Using one 225 and three 205 is not to be recommended on the Subaru 4WD system!
IIRC the tyre size as standard on the classic was 215/45-16 so ideally, you need 215/40-17 to retain as near as dammit, the same rolling radius.
If you get that alloy, check it matches the width and offset (ET number) of your existing wheels.

JohnD

alcazar

iTrader: (2)

yes, you can use either.

I mistyped in my first post, newage cars do, indeed use 225/45 tyres.

ace1981

Thanks to all.

WRXrowdy

iTrader: (2)

New age STI use 225/45 17, WRX use 215/45 17

alcazar

iTrader: (2)

OK, cheers bud.