Question about wheel offset

[BMracing]

Hey,

I am interested in buying some used team dynamics pro race 2 wheels for our track car. They were previously fitted to a Suzuki Ignis. Obivously i've checked that the stud pattern is the same but what are the limits of offset on an e30? What is the ideal offset? The OE offset on the ignis is 45 which might be a bit much?

Thanks guys,

Max

[junkjimmy]

Dude people say 5mm+ of negative offset can cause wheel kick

[BMracing]

Hmmm, not good, so negative offset will effectively bring the wheels further into the arches and narrow the track width which I don't want, especially for a track car

[junkjimmy]

No dude it widens the track so the load is not in the centre of the wheel rim causing wheel kick search google for an offset calculator

[BMracing]

I'm confused now! I just used this calculator;

http://www.1010tires.com/WheelOffsetCalculator.asp

If you keep the old and new wheel widths the same and put in a bigger offset for the new wheel it says the inner clearance is less and the outer clearance obviously more (retracts). So surely this is narrowing the track width?!

[StuBeeDoo]

The correct offset for 7" rims on an E30 is 24mm.
What width are the wheels you are looking at? Required offset changes for different rim widths.
If the Suzuki rims are 7" wide, you'd need to use 20mm spacers to fit them (ideally) on the E30.
HTH
Stuart.

[junkjimmy]

Dude ive got some 7" rims with an offset of 15mm which gives 9mm of negative offset so your rims will work with spacers depending on width .The load from the car has to be in the centre of the rim in an ideal world posative offset is not as bad as negative. The rims i had fitted with the 9mm of negative offset gave my car a wider track which caused wheel kick as they had 205 tyres fitted they caught the front of the of the wheel arch liner on full lock so i changed them for 15" bbs the car is much more predictable now

[StuBeeDoo]

Dude ive got some 7" rims with an offset of 15mm which gives 9mm of negative offset

Negative offset is when the centre-line of the rim is outside the hub centre-line.
What you had there was exactly what it says on the tin..... 15mm offset. Ie - 9mm less offset than 15x7 et24 BBS rims. That isn't negative offset.
If you had 9mm negative offset, the rims would have been 33mm further out of the arch.

The rims i had fitted with the 9mm of negative offset gave my car a wider track which caused wheel kick as they had 205 tyres fitted they caught the front of the of the wheel arch liner on full lock so i changed them for 15" bbs the car is much more predictable now

I've been running 15x7 et13 wheels with 205/55x15 tyres for over a year and never had any kick-back or contact issues. TBH, I can't tell any difference driving my car on et13's to driving one with et24's.
You're right about the increased track though.

[old_skool]

Dude ive got some 7" rims with an offset of 15mm which gives 9mm of negative offset

Negative offset is when the centre-line of the rim is outside the hub centre-line.
What you had there was exactly what it says on the tin..... 15mm offset. Ie - 9mm less offset than 15x7 et24 BBS rims. That isn't negative offset.
If you had 9mm negative offset, the rims would have been 33mm further out of the arch.

The rims i had fitted with the 9mm of negative offset gave my car a wider track which caused wheel kick as they had 205 tyres fitted they caught the front of the of the wheel arch liner on full lock so i changed them for 15" bbs the car is much more predictable now

I've been running 15x7 et13 wheels with 205/55x15 tyres for over a year and never had any kick-back or contact issues. TBH, I can't tell any difference driving my car on et13's to driving one with et24's.
You're right about the increased track though.

So the lower the offset, the wider the track? Ie. ET24 will give wider track than ET13?


Paracetamol please

[d6dph]

No lower the ET = wider track!

Pushes the wheel further away from the hub

[DaveD]

There is an even better calculator in the links section

[StuBeeDoo]

So the lower the offset, the wider the track?

Yep.

Ie. ET24 will give wider track than ET13?

Wrong way round. et24 is higher offset than et13.
Going from et24 to et13 will give you 22mm wider track.

[BMracing]

This is what I thought, thanks for clearing that up guys. So if I get these wheels i'll need spacers for certain, its just a matter of how big they'll need to be as the guy doesn't know the offset. Looking at the rimstock website the offset should be no more than 45. So I may need some fairly big spacers.
Anyone had any experience of these?
Eibach spacers are supposed to be good but the idea of them and long bolts seems a bit dodgy to me.

[BMracing]

Oh Stubeedoo yes they are 7x16 inch rims.

[A1BMW325iSport]

BMracing - sorry to jump in on your topic

StuBeeDoo you seem to know your stuff, i'm thinking about getting these off ebay...

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0178782502

they are 7.5x17 not sure they offset yet, emailed to ask seller. what offset should they be for 7.5 width?

i have a new set of 215/40/17 tyres ready. would they fit 325 sport with standard sport suspension and not rub with 215 tyres?

thanks

[junkjimmy]

Dude if you take a close look at the diagram on this link you will find my et 15 rims were negative offset http://www.tirefactory.com/img/offset.gif

[StuBeeDoo]

what offset should they be for 7.5 width?

7.5" rims on an E30 should be somewhere close to et18.
Having said that, IIRC 16" Hartge's (which are 7.5") are et25. So I suppose anything lower than et25 will be fine.

[StuBeeDoo]

Oh Stubeedoo yes they are 7x16 inch rims.

As above then. You'll need 20mm spacers to get the right offset for the E30.

[A1BMW325iSport]

what offset should they be for 7.5 width?

7.5" rims on an E30 should be somewhere close to et18.
Having said that, IIRC 16" Hartge's (which are 7.5") are et25. So I suppose anything lower than et25 will be fine.

cheers he just got back to me saying they are et20

[BMracing]

Yup, thanks Stuart.
So does anyone think big spacers are an issue then? I just get the impression they wouldn't be strong enough, especially on the track.

[StuBeeDoo]

So does anyone think big spacers are an issue then?

Not as long as you don't mind replacing wheel bearings more often than usual. I suppose if the car is purely for track use it won't be as much of an issue as it would be on a 10k-a-year road car.

[BMracing]

Cheers mate, doesn't sound so bad.