Why is high rear wheel offset common? - Honda CRZ Forum: Honda CR-Z Hybrid Car Forums

zoltiz · 05-05-2011, 01:09 PM

So this bugged me ever since I bought my first set of wheels long time ago - why is it common for OEM suspension on majority of mainstream Japanese and American cars to have a very high (negative) offset for the rear wheels?

Even the cheap FWD VW or Audi would have a much more refined looking rear end. Between the offset and wheel arch gap it just puzzles me what drives automotive designers to make decisions like that. Not like US and Japanese roads are horrible and require a lot of clearance. And it doesn't cost any more or less to manufacture a different offset wheel and to have an even wheel arch gap.

So if you have some insight in this, please share, but for now I'll be buying $150 spacers...

roddy · 05-05-2011, 01:29 PM

i don't knwo the exact answer, but please clarify what you mean by very high (negative) offset?

zoltiz · 05-05-2011, 01:57 PM

Quote:

Originally Posted by roddy

i don't knwo the exact answer, but please clarify what you mean by very high (negative) offset?

Commonly known as tucked in wheels. Which usually is signified by a high offset (ET45 and higher).

Also I might be on crack saying that it's negative offset. It's not. So please ignore that part.

kyo · 05-05-2011, 07:26 PM

negative offset is the 'deep dish' look

negative - more towards brakes [ |]
positive - towards outside of car [| ]
zero - centerline with the wheel [ | ]

Most cars I see have a pretty large positive offset, such as the cr-z with the flat faced look. OEM will do this because it creates less pressure on the lugs and steering system.

negative offset moves the tire away from suspension/brake components and widens the stance, more pressure on lugs/steering, wider turning radius ... can allow wider tires, and some prefer the look.

Taken from memory of reading faq's and wikis

It would be beneficial to show/link some pictures ... 1000 words and all that

Hois's rims, for example, are positive offset and nearly flush with body of car

this would be an example of negitive offset

as well as

SennaFan · 05-05-2011, 07:32 PM

Wheel Tech - Offset

zoltiz · 05-05-2011, 07:49 PM

This still doesn't address the main reason for this thread - why the hell do OEMs tend to have the tucked in rear wheels on the FWD cars?

Worst case they can move the hubs out if they want to avoid the stress on lug studs and such and still have the wheel more or less flush with the body of the car. (I tried really hard to avoid using the word flush since it became and abomination with the 'hellaflush' stuff).

Scotty001 · 05-05-2011, 08:00 PM

^Dunno, but was the first thing I fixed... Maybe it is an aftermarket conspiracy..

GoHuskies · 05-05-2011, 09:27 PM

I didn't know what the topic was until the word flush was used

sohcsol · 05-05-2011, 10:10 PM

A few of reasons I can think of...

1) Wider track in the front induces understeer, aka makes a "safer" vehicle for the common driver in an emergency situation.

2) Keeping the unsprung weight closer to the pivot point of the suspension technically reduces the force of load on the spring and shock, and should produce a more reactive suspension.

3) ... I cant think of anything else, it truly does look hideous.

SFLA-Z · 05-06-2011, 12:30 AM

Also, positive offset combined with 'quick and dirty' McPhearson strut design gives more space in the engine bay up front, with rear wheels to match.

05-05-2011, 01:09 PM	#1 (permalink)
zoltiz Senior Member Join Date: Oct 2010 Location: Atlanta, GA Posts: 482	Why is high rear wheel offset common? So this bugged me ever since I bought my first set of wheels long time ago - why is it common for OEM suspension on majority of mainstream Japanese and American cars to have a very high (negative) offset for the rear wheels? Even the cheap FWD VW or Audi would have a much more refined looking rear end. Between the offset and wheel arch gap it just puzzles me what drives automotive designers to make decisions like that. Not like US and Japanese roads are horrible and require a lot of clearance. And it doesn't cost any more or less to manufacture a different offset wheel and to have an even wheel arch gap. So if you have some insight in this, please share, but for now I'll be buying $150 spacers... __________________ ______________ '11 CR-Z EX 6MT \| '05 Lotus Elise

05-05-2011, 01:29 PM	#2 (permalink)
roddy Senior Member Join Date: Oct 2010 Location: san jose, ca Posts: 1,018	i don't knwo the exact answer, but please clarify what you mean by very high (negative) offset? __________________ need an avatar? take one from my flickr have questiosn? fb me: www.facebook.com/roddy3

05-05-2011, 07:49 PM	#6 (permalink)
zoltiz Senior Member Join Date: Oct 2010 Location: Atlanta, GA Posts: 482	This still doesn't address the main reason for this thread - why the hell do OEMs tend to have the tucked in rear wheels on the FWD cars? Worst case they can move the hubs out if they want to avoid the stress on lug studs and such and still have the wheel more or less flush with the body of the car. (I tried really hard to avoid using the word flush since it became and abomination with the 'hellaflush' stuff). __________________ ______________ '11 CR-Z EX 6MT \| '05 Lotus Elise

05-05-2011, 10:10 PM	#9 (permalink)
sohcsol Senior Member Join Date: Nov 2010 Location: Sarasota, FL Posts: 564	A few of reasons I can think of... 1) Wider track in the front induces understeer, aka makes a "safer" vehicle for the common driver in an emergency situation. 2) Keeping the unsprung weight closer to the pivot point of the suspension technically reduces the force of load on the spring and shock, and should produce a more reactive suspension. 3) ... I cant think of anything else, it truly does look hideous. __________________ 2011 CR-Z EX, 6MT, CBP, #7960

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05-05-2011, 07:26 PM	#4 (permalink)
kyo Member Join Date: Apr 2011 Posts: 38	negative offset is the 'deep dish' look negative - more towards brakes [ \|] positive - towards outside of car [\| ] zero - centerline with the wheel [ \| ] Most cars I see have a pretty large positive offset, such as the cr-z with the flat faced look. OEM will do this because it creates less pressure on the lugs and steering system. negative offset moves the tire away from suspension/brake components and widens the stance, more pressure on lugs/steering, wider turning radius ... can allow wider tires, and some prefer the look. Taken from memory of reading faq's and wikis It would be beneficial to show/link some pictures ... 1000 words and all that Hois's rims, for example, are positive offset and nearly flush with body of car this would be an example of negitive offset as well as

05-05-2011, 07:32 PM	#5 (permalink)
SennaFan Member Join Date: Aug 2010 Posts: 59	Wheel Tech - Offset

05-06-2011, 12:30 AM	#10 (permalink)
SFLA-Z Senior Member Join Date: Feb 2011 Location: West Palm Beach, FL Posts: 288	Also, positive offset combined with 'quick and dirty' McPhearson strut design gives more space in the engine bay up front, with rear wheels to match.