Help With Wheel Offset

[Rob]

hi all,

does anyone know what the effect of a smaller wheel offset would be on the IS i.e 40MM instead of 45MM?

and if i combine that with a 30mm drop - what would happen then - or should i just get some 5MM spacers?

thanks for the help.

rob

[TonyGoose]

hi all,

does anyone know what the effect of a smaller wheel offset would be on the IS i.e 40MM instead of 45MM?

rob

Rob.

See you got those springs on eBay .. have fun :D

Thought about it but couldn't go bidding against fellow club members

Anyway, offset ...

the distance between the mounting face of a wheel and it's centreline.

If you increase the offset, you reduce how much the wheel sticks out.

So, if you fit a 10mm wider wheel, with 5mm more offset, it sticks out the same.

The additional 10mm would all be on the inside ... watch for fouling on suspension.

Or a 10mm wider wheel maintaining original offset, 5mm is added inside and out.

Generally, it's desirable to maintain original offset, specially up front.

If you mess with offset here, you may upset steering and thus handling.

Imagine the point about which the steering pivots is also the centreline through the wheel.

If you steer while stationary, the wheel will turn 'on the spot'.

If you change offset, the wheel has to move in an arc to steer.

Well i know what i mean Kind of difficult to explain

This ( http://www.tirerack.com/wheels/tech/offset.htm ) may help explain offset ...

I've always tried to keep to the vehicle manufacturers original offset ...

or as close as possible to it with regard to fouling of suspension / arches etc.

Is that any kind of help ?? :eerrrmm:

[javadude]

Hi fluff

Guess you're finding it difficult to find a wheel you like with the right offset? I just had that problem too. Every wheel I liked and could afford had the wrong offset. Only hideous or expensive wheels had the right offset! <_< (Finally managed it though - the kosei's come in a 45.)

[GRiM]

Are these questions for the new wheels Rob? (on eBay...)

Lettuce know if you get them :D

[Monster-Mat]

FRONT

width | offset | tires range (width)

7 = 40 and up 215-225

7.5 = 42 and up 215-235

8 = 43 and up 215-235

8.5 = 45 and up 215-225

REAR

7 = 40 and up 215-225

7.5 = 40 and up 215-235

8 = 42 and up 215-245

8.5 = 45 and up 225-265 (255-265 requires rolling or shaving lip)

9 = 49 and up 235-275 (MAY require rolling or shaving lip)

9.5 = 52 and up 245-285 (MAY require rolling or shaving lip, 285 may require more modification)

10 = 45 and up 255-315(requires pulling fender)

COMBINATIONS CAN BE PLAYED WITH FOR ROLLING RADIUS.

I.E, use of 35 profile tyres on the back with a 255 is equal to the rolling radius of a 225/40/18 on the front

[Rob]

hi Gord, yes these Q's are for the wheels that were on ebay(germany).

the wheels are 7.5X17 but the offset is 40 mm, sorry Tony i follow roughly what you said, so if i have a 7.5 wide wheel but the offset is 5mm less, then the total effect will be that the wheel is roughly in the same position???? slight difference - so best for me to fit a spacer or not???

[TonyGoose]

hi Gord, yes these Q's are for the wheels that were on ebay(germany).

the wheels  are 7.5X17 but the offset is 40 mm, sorry Tony i follow roughly what you said, so if i have a 7.5 wide wheel but the offset is 5mm less, then the total effect will be that the wheel is roughly in the same position???? slight difference - so best for me to fit a spacer or not???

Rob.

Yeah you got the idea ...

A few mm isn't gonna make a huge difference anyway - ooh err missus

Personally, i'd avoid spacers where possible.

Unless very good quality, they're likely to introduce balance problems.

Also ensure wheels are hubcentric ...

That is to say they sit correctly centred on the hub by themselves.

Most wheels come with a ring which fits inside the centre hole to achieve this.

Make sure it's the right one and it's not the nuts forcing the wheel to centre on the hub.

Good luck.

[Bazza-old]

the wheels are 7.5X17 but the offset is 40 mm, sorry Tony i follow roughly what you said, so if i have a 7.5 wide wheel but the offset is 5mm less, then the total effect will be that the wheel is roughly in the same position???? slight difference - so best for me to fit a spacer or not???

no it works the other way round

if you put say a 5mm spacer on with a 40mm offset you will end up with a 35mm offset