15 x 7.5J ET30 Wheels

[Alex Knight]

Hi all,

I am thinking about changing my wheels to Ultralite F1s, however I have a concern about fitment.

My current wheels specs are:

7.0J x15"
ET35

Absolutely zero scrubbing, and it looks like this when fully loaded:



The wheels I am looking at are:

7.5J x15"
ET30

I am concerned that the 5mm of additional offset and the 0.5" of additional width may cause scrubbing at full chat?

[ManInDandism]

Keeping it simple and from a purely wheel measurement perspective (also since no mention of tyres sizes).

Calculation involves wheel widths and ET nos.

123.9 | 53.9 (current) vs 125.25 | 65.25 (new)

These are in mm. '|' is where wheel mates to the hub, first number inside part of wheel, second outside part. So new wheel sticks out from wheel arch a further 11.35mm (65.25 - 53.9) but neglible difference inside the arch.

As clear as mud and I think this is right

[Alex Knight]

That's actually really helpful stuff. Thanks a bunch, much appreciated.

My main concern is fouling the outside of the wheelarch. I'm fairly comfortable that there will be enough clearance to the strut.

I think 11mm further out may be close, but do-able.

[JB21]

ET30-7.5J will be tight, mine below with ET20-7J wheels...

You cannot view this attachment.

You cannot view this attachment.

You cannot view this attachment.

You cannot view this attachment.

[ManInDandism]

ET30-7.5J will be tight, mine below with ET20-7J wheels...

You cannot view this attachment.

You cannot view this attachment.

You cannot view this attachment.

You cannot view this attachment.

Doing the same calculation here you get 108.9 | 68.9. So small offset means it sticks out more than the new one @Alex Knight Is considering despite being narrower.

Calculation not that difficult. Wheel widths are measured in inches and offsets in mm so need to convert to the same unit. If ET no. was 0 then wheel would mount exactly half way along the width. But as it's usually a positive number, mounting point shifts towards wheel face by X mm where X is ET number. Makes sense if you look at a rim.

[JB21]

ET30-7.5J will be tight, mine below with ET20-7J wheels...

You cannot view this attachment.

You cannot view this attachment.

You cannot view this attachment.

You cannot view this attachment.

Doing the same calculation here you get 108.9 | 68.9. So small offset means it sticks out more than the new one @Alex Knight Is considering despite being narrower.

Calculation not that difficult. Wheel widths are measured in inches and offsets in mm so need to convert to the same unit. If ET no. was 0 then wheel would mount exactly half way along the width. But as it's usually a positive number, mounting point shifts towards wheel face by X mm where X is ET number. Makes sense if you look at a rim.

His new wheel would sit 10mm further in the wheel arch than mine above. Also tyres are all different overall widths so can protrude more if say they have rim protectors.

IMO a ET30 would rub on the arches.

[Alex Knight]

Thanks for the advice everybody.

Think I am going to leave it, unless I can find a reasonably priced set of genuine Enkei RPF1s in 15x7.0J ET35 (improbable).