Tyre Sizes And Arches And Offset

[ScoobySounds]

I'm very excited now about my next mod spree - the handling!! whoo hoo!

but one problem I need to get sorted is the arch grinding on the tyres after a sharp dip in the road or a landing after a rise - escpecially if the car has passangers. I've had them ground right back so its not as bad as it could be, but still there. I wanna be able to get air on this thing not baby it. and escpecially when I get the new coilovers its gonna sit lower too.

firstly; I got the superleggera's from peter fai17 (ie a newage) so the offset is probably out a bit for a classic. So has anyone ever heard of machining the wheels to take the Offset back a bit? If so what do you know about it?

second; I wonder if I can safely change the tyre size on these wheels and if that is likely to help? They are 225/40/18 just now. Does anyone know If I could put, say, 215/35/18 on the same rims and how that would affect the handling and the grinding?

I'm looking to get the goodyear asymmetric eagle f1's and don't want to rip em up on the arches!

Hopefully I'll be all done by the time Knockhill 15th June comes around!!

[braveheart]

I'm very excited now about my next mod spree - the handling!! whoo hoo!

but one problem I need to get sorted is the arch grinding on the tyres after a sharp dip in the road or a landing after a rise - escpecially if the car has passangers. I've had them ground right back so its not as bad as it could be, but still there. I wanna be able to get air on this thing not baby it. and escpecially when I get the new coilovers its gonna sit lower too.

firstly; I got the superleggera's from peter fai17 (ie a newage) so the offset is probably out a bit for a classic. So has anyone ever heard of machining the wheels to take the Offset back a bit? If so what do you know about it?

second; I wonder if I can safely change the tyre size on these wheels and if that is likely to help? They are 225/40/18 just now. Does anyone know If I could put, say, 215/35/18 on the same rims and how that would affect the handling and the grinding?

I'm looking to get the goodyear asymmetric eagle f1's and don't want to rip em up on the arches!

Hopefully I'll be all done by the time Knockhill 15th June comes around!!

I have Oz Super T 215/35/18 with Parada Spec 2 on mines with the green Tien and all the whitline goodies and the handeling is exellent however the wheels offset is for the Classic ... so cant really answer about the offset..

if that helps..dont get any rubbing at all..

Chris

[oobster]

I may be wrong here (I do a lot of browsing here & on SNet but not much contributing) but I always thought the offset was the same for classic or newage, but the rule was always 215 for a classic & 225 for a newage.

[thewelsho]

I may be wrong here (I do a lot of browsing here & on SNet but not much contributing) but I always thought the offset was the same for classic or newage, but the rule was always 215 for a classic & 225 for a newage.

I had 215/45/17 on my car from new. However, my 17" track wheels (04 STi) are 225/45 and my 18s are 225/40. I guess that means you can mix and match. I dunno what offset means though, someone care to explain?

[ScoobySounds]

I have Oz Super T 215/35/18 with Parada Spec 2 on mines with the green Tien and all the whitline goodies and the handeling is exellent however the wheels offset is for the Classic ... so cant really answer about the offset..

if that helps..dont get any rubbing at all..

Chris

nice one - I've heard those tyres are great!

I may be wrong here (I do a lot of browsing here & on SNet but not much contributing) but I always thought the offset was the same for classic or newage, but the rule was always 215 for a classic & 225 for a newage.

ahhhh! i've not heard that before! where are these 'rules', because I never got a copy

so can I put 215's on my current rims?

[ScoobySounds]

I had 215/45/17 on my car from new. However, my 17" track wheels (04 STi) are 225/45 and my 18s are 225/40. I guess that means you can mix and match. I dunno what offset means though, someone care to explain?

The technical description of offset is the sticky-outeyness of the wheel !

how much it 'sticks' out.

or to put it another way

how much it sticks 'out'

[ScoobySounds]

John, so as per oobster, you should have had 225's on yours?

maybe nothing is necessarily so, ay.

[oobster]

I wouldnt say that what I said earlier is 100% accurate, it's just my understanding from reading lots of posts. I may be wrong.

[thewelsho]

John, so as per oobster, you should have had 225's on yours?

maybe nothing is necessarily so, ay.

When I got my car brand new (MY06 WRX), still in the wrapper, it had 215/17/45 tyres on it. 225s on it now though. So offset is changed using spacers, yes? I thought the idea of that ws to make the wheel fit over bigger brakes. I'd have though machining wheels to bring them in closer to the hub s it where, would be a trifle dodgy! Making the wheel thinner might not be a great idea, especially when they are under load. Of course, I might be getting the wrongend of the stick - or wheel!

Edited April 29, 2008 by TheWelsho

[ScoobySounds]

I'd have though machining wheels to bring them in closer to the hub s it where, would be a trifle dodgy!

good point,

if I machined them they prob would be too close to the the AP calipers.

in that case, I might get the 215/35/18 tyres and see how we go.

I guess you'd use spacers for more offset, but new wheels for less offset

[fai17]

215 will fit on your current wheels m8...

[addison]

I'm very excited now about my next mod spree - the handling!! whoo hoo!

but one problem I need to get sorted is the arch grinding on the tyres after a sharp dip in the road or a landing after a rise - escpecially if the car has passangers. I've had them ground right back so its not as bad as it could be, but still there. I wanna be able to get air on this thing not baby it. and escpecially when I get the new coilovers its gonna sit lower too.

firstly; I got the superleggera's from peter fai17 (ie a newage) so the offset is probably out a bit for a classic. So has anyone ever heard of machining the wheels to take the Offset back a bit? If so what do you know about it?

second; I wonder if I can safely change the tyre size on these wheels and if that is likely to help? They are 225/40/18 just now. Does anyone know If I could put, say, 215/35/18 on the same rims and how that would affect the handling and the grinding?

I'm looking to get the goodyear asymmetric eagle f1's and don't want to rip em up on the arches!

Hopefully I'll be all done by the time Knockhill 15th June comes around!!

http://www.carbibles.com/tyre_bible_pg2.html

This site will explain all

Edited April 29, 2008 by addison

[ScoobySounds]

http://www.carbibles.com/tyre_bible_pg2.html

This site will explain all

Excellent link mate, thanks!!

I was surprised to read about the subaru tyre pressures.. hang on i'll quote;

Tyre pressure and gas-mileage.

For the first two years of our new life in America, I'd take our Subaru for its service, and it would come back with the tyres pumped up to 40psi. Each time, I'd check the door pillar sticker which informed me that they should be 32psi front and 28psi rear, and let the air out to get to those values. Eventually, seeing odd tyre wear and getting fed up of doing this, I asked one of the mechanics "why do you always over-inflate the tyres?" I got a very long and technical response which basically indicated that Subaru are one of the manufacturers who've never really adjusted their recommended tyre pressures in line with new technology. It seems that the numbers they put in their manuals and door stickers are a little out of date. I'm a bit of a skeptic so I researched this on the Internet in some of the Impreza forums and chat rooms and it turns out to be true. So I pumped up the tyres to 40psi front and rear, as the garage had been doing, and as my research indicated. The result, of course, is a much stiffer ride. But the odd tyre wear has gone, and my gas-mileage has changed from a meagre 15.7mpg (U.S) to a slightly more respectable 20.32 mpg (U.S). That's with mostly stop-start in-town driving. Compare that to the official quoted Subaru figures of 21mpg (city) and 27mpg (freeway) and you'll see that by changing the tyre pressures to not match the manual and door sticker, I've basically achieved their quoted figures.

*chin stroking*

[thewelsho]

Excellent link mate, thanks!!

I was surprised to read about the subaru tyre pressures.. hang on i'll quote;

*chin stroking*

Well now, guess who's going down to the garage to over infalte their tyres?

You guessed it! See you all later!!!!!!!