Noob offset questions

[chris davey]

I understand the principle of offsets when going to a wider wheel but what about going to a smaller one? Does it matter at all? Haven't worked out offset of the front wheels I currently have yet but they are 14X7's and I will be getting skinny wheels like 4 to 5" wide.

Also, if I have a 15X6 with +38 offset, what offset do I require if I move to a 15X7? I want to keep the outside of the wheel in the same position and have the extra width on the inside.

Thanks

Chris

[stradlater]

it's all down to measuring how much space you have in front and how much behind as to whether you'll need to make an offset change or not.

A bitch of a thing to work out, I'm trying to work it out myself atm.

[stradlater]

Up front though, I wouldn't think the offset will matter if going from front runners.

[chris davey]

Also, opinions on using space saver spare wheels with good tyres rather than the space saver tyres. Is this ok? Is it only the tyre that is speed limited or the wheel as well?

Can get commo wheels in 15X4 but unsure of offset?

[chris davey]

Thanks for quick response

Ok so with this example

15X6's with +38

Then use 15X7's with +38. WIll that mean that the extra 25.4mm of width will be spread evenly either side or not?

[CrUZida]

15x7 +38 will have 12.7mm more width either side.

To keep the inside in the same position you'll need 15x7 +25
To keep the outside in the same position you'll need 15x7 +51

[Hen]

15X6's with +38

Then use 15X7's with +38. WIll that mean that the extra 25.4mm of width will be spread evenly either side or not?

Yes.

Rim edge will sit a half inch further out both ways.

To keep the outside edge at the same point and have an inch extra inboard, you would need a 15 by 7 in +50.

Hen

EDIT - beaten by Cruz

[WDE_BDY]

Remember, rim width is less important than tyre width. A 5 inch rim and a 7 inch rim with the same offset will have the same clearance with the same tyre. Somewhere here I posted how to measure the offset for a rim, look it up and you should have no problems checking clearances.

Callum

[oldcorollas]

and if this is for front runners, the distance the tyre is from steering axis might need consideration....

skinny tyres further out might be more affected by bumps and surface changes than a skinny tyre closer to the strut. (since the centre of contact patch/force changes distance from the strut)

[Wezelton]

PM me chris or hit me up on msn i'll help ya work it out

[Smokey228]

Here is something i used wen i was trying to work out offsets and shit. i dunno if u can use it but it might be worth something... Click Here...

[chris davey]

and if this is for front runners, the distance the tyre is from steering axis might need consideration....

skinny tyres further out might be more affected by bumps and surface changes than a skinny tyre closer to the strut. (since the centre of contact patch/force changes distance from the strut)

So does anyone know the offset of a space saver? I was under the impression that they are as negative as possible to try and keep the same track as a wider tyre.




rep given

[oldcorollas]

i dunno about negative...

most space savers are for cars with FWD offsets, which are nowdays like +48, +51 etc, which is huge!, so the space savers may be close to zero (being so skinny, they can't have too much anyway)....

do falcadores have skinny space savers nowadays? are all space savers (generally) the same?

[CrUZida]

I'm pretty sure all space savers are 0 offset.

I can check when I get home though.

But I have a stock 1983 MZ11 Soarer space saver, not a newer Silvia or Honda.

[chris davey]

New Commodores have 15X4” wheels which would be good. They are $115 each though and they couldn’t tell me what offset.

I have some commodore pursuit wheels for the back at the moment so the options are to use them which are 15X6 +41, old wheels are 15X6 +36. Should be fine as I have some room on the inside of the arch. I am going from 225/60 15’s to 225/70 15’s which is about 1.8” total diameter larger but I think that should still be ok.

Then get some Commodore space savers for the front.

This leads me to my next question? Can you run a cross ply front tyre and a radial tyre? Advantages and disadvantages?

Other option is to find some Japanese space savers in 5 X114.3mm for the front and some Ford pursuit rims for the rear in 15X6 or 15X7.