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Correct Offset

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Old 24-03-2010, 11:19 AM
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BJAS
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Default Correct Offset

The OEM rims on the Sapphire are 7Jx15H2E40; meaning a 40 mm offset.

What is the correct offset if you go to 8x16 or 8x17 inch rims.

I am thinking Revolution Millenniums, Compomotive 1781 or Speedline 2108.

Thanks
Old 24-03-2010, 12:19 PM
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Ridgey
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I've been running et32 on my 7x18, and have the same offset on some new 8x16 rims.
Most run 32 - 35 et.
Old 24-03-2010, 02:11 PM
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Mike1
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Originally Posted by Ridgey
I've been running et32 on my 7x18, and have the same offset on some new 8x16 rims.
Most run 32 - 35 et.
What tyres are you switching to on your 16s Dave?
Old 24-03-2010, 02:22 PM
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I always thought that for eight inches you need ET25 on a Sapph - same as Escort Cossie alloys. Is this wrong?

Charlie
Old 24-03-2010, 03:47 PM
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Originally Posted by Char1ie
I always thought that for eight inches you need ET25 on a Sapph - same as Escort Cossie alloys. Is this wrong?

Charlie

I know lots of people use Escos alloys on their Sapphires but I thought they weren't 'quite' the right offset for a 4-door ( although I realize the Escos is based on a 4x4 Saph ).
Is there any chance of arch interference or is that only with excessive lowering or is there some unfavourable geometry steer issues involved as well?
Old 24-03-2010, 03:49 PM
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By the way, further to Charlie's Wheel Weights post is there anyone who has ever weighed a std escos wheel and tyre who can informationalise us?
Old 24-03-2010, 06:42 PM
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Captain500rs
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I would say ET35 and was advised to use this offset off Martin at Reyland, had this offset on my 8x17, and now on 8x18.

Revolution Milleniums run a GrpA offset of Et30.

Last edited by Captain500rs; 24-03-2010 at 06:43 PM.

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Old 24-03-2010, 08:31 PM
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Thanks for the replies. There seems to be many people using ET32 to 35. I guess if there are no problems wit arch interference then that is the way to go,
Old 24-03-2010, 09:14 PM
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pacwest
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handy little calculator:

http://www.1010tires.com/WheelOffsetCalculator.asp
Old 25-03-2010, 06:42 AM
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Originally Posted by pacwest
Very useful little tool.

According to the calculator:

An 8 inch rim with 32 mm offset reduces the inner clearance by 5 mm and extends the outside edge of the wheel an extra 21 mm.

An 8 inch rim with 25 mm offset gives 2 mm of extra clearance on the inside and extends the outer edge of the wheel an extra 28 mm.

I haven't looked at the car and measured; but it seems to me that the 25 mm offset on 8 inch rims might well be problematic. A 28 mm extension of the outer edge of the wheel is a lot.

The 32 mm offset seems more likely to work but I really, really, really don't want any fouling of the arch.

Is anyone running 8 x 17 ET 32 rims having issues with fouling; either inside or on the arch?

with the standard rims, how much clearance is there on the inside, and how much room do you have to play with on the outside?

Last edited by BJAS; 25-03-2010 at 06:47 AM.
Old 25-03-2010, 08:59 AM
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Originally Posted by BJAS
Very useful little tool.

According to the calculator:

An 8 inch rim with 32 mm offset reduces the inner clearance by 5 mm and extends the outside edge of the wheel an extra 21 mm.

An 8 inch rim with 25 mm offset gives 2 mm of extra clearance on the inside and extends the outer edge of the wheel an extra 28 mm.

I haven't looked at the car and measured; but it seems to me that the 25 mm offset on 8 inch rims might well be problematic. A 28 mm extension of the outer edge of the wheel is a lot.

The 32 mm offset seems more likely to work but I really, really, really don't want any fouling of the arch.

Is anyone running 8 x 17 ET 32 rims having issues with fouling; either inside or on the arch?

with the standard rims, how much clearance is there on the inside, and how much room do you have to play with on the outside?
Here's an old post from JjdeCox75 who had Escort Cosworth alloys on a Sapphire

https://passionford.com/forum/techni...-sapphire.html
Old 25-03-2010, 12:45 PM
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Mike1
Gonna use 225/45 with the 16's, Kumho or Toyo track tyres
Would have prefered 225/40, but don't seem to be able to get them in 16's

BJAS
8x17 with 225/35 were OK on mine, though i did ease the front arches a little on the inner lip. BUT it is purely dependant on the tyre size and ride height you have. And the age of springs as they will sag with time and run lower.
Old 28-03-2010, 09:26 AM
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Originally Posted by Ridgey
Mike1
Gonna use 225/45 with the 16's, Kumho or Toyo track tyres
Would have prefered 225/40, but don't seem to be able to get them in 16's
What brakes have you got Dave? What was behind the decsion to go an inch smaller?
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