Downsizing Rims

sheffield

Active Member
Jan 11, 2017
49
0
I am thinking about down sizing the 300's 19" rims to 18", am i correct that changing from;

235/35 R19 Tyres on 8Jx19 ET50 Rims (OEM)

to

235/40 R18 Tyres on 8Jx18 ET?? -

Rims would maintain the overall diameter, and therefore wouldn't cause any errors in speedo reading etc.

Does anyone know if I would need to keep the offset the same, or what offset I would need to clear the brakes with 18" rims?

Has anyone changed their mk3 down from 19 to 18s?
 

weasley

Active Member
May 19, 2017
137
4
South Oxfordshire
Those two tyre sizes are pretty much exactly the same circumference (0.3% theoretical difference).

Offset is another matter. Ideally you would stay with the OEM offset, because this is about more than just brake and bodywork clearance, it is a part of the overall steering and suspension geometry and going away from OEM could lead to unexpected handling, especially in the case of a tyre deflation or blowout.
 

sheffield

Active Member
Jan 11, 2017
49
0
Those two tyre sizes are pretty much exactly the same circumference (0.3% theoretical difference).

Offset is another matter. Ideally you would stay with the OEM offset, because this is about more than just brake and bodywork clearance, it is a part of the overall steering and suspension geometry and going away from OEM could lead to unexpected handling, especially in the case of a tyre deflation or blowout.

Thanks, I currently have one of the OEM rims off the car as has a blowout down the m1 ayesterday, where would I be able to find the offset value?

Thanks
 

misiakupatego

Active Member
Mar 5, 2017
65
0
Check Borbet BS5 18"

ET50, 8Jx18, 225/40

DSC_0167.jpg


DSC_0170.jpg



On Cupra 265:

cupra_pika_21.jpg


Anybody see noticeable comfort change when swapping from 19" to 18" in Cupra?
 
Last edited:

rryans11

MK3 Leon Cupra 290
Feb 4, 2012
238
9
UK
Thanks, useful website! I was planning on keeping the width the same at 8" to keep the grip!

I've been running my 280 on 18's from purchase and I've no problems at all. She's running on 225/40/18 tyres, wheels are 18x8j ET45 BBS SRs'

Also no real issues with grip, she lifts well from a standstill with no axle tramp unless you mash the throttle to the floor in first.
 
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sheffield

Active Member
Jan 11, 2017
49
0
If dropping from a 50 ET to a 45 ET, how beneficial/needed would 5mm spacers be?

Both rims being 8" diameter.
 

eltawater

Full and wholesome member
May 1, 2008
305
45
If you go from ET50 to ET45, doesn't that mean the rims will stick out more from the wheel arch? So adding spacers is going to stick out even further?
 

sheffield

Active Member
Jan 11, 2017
49
0
If you go from ET50 to ET45, doesn't that mean the rims will stick out more from the wheel arch? So adding spacers is going to stick out even further?

I thought the larger the offset, the further away from the car the centre line of the rim would be?

Am I getting it the wrong way round?
 
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