Wheel Offset

bill-robinson, Sep 23, 2:43pm
as in the title,what is it for! why does it vary from model to model!
Belky could you please re enter your reasons!
bellky, Sep 23, 3:58pm
Okay then, this was my effort:
bill-robinson, Sep 23, 4:03pm
Thanks Belky
Should stop the hijacking of the trailer thread that had exceeded its best by.
unbeatabull, Sep 24, 2:28am
You know what it physically is right! The centre of wheel where it bolts in in relation to where it is inside the rim.

Basically a higher offset allows a wider wheel to be fitted within the same width/panel constraints. We all know the benefits of a wider wheel & tyre (more loading, grip etc)

Most manufacturers that design cars for handling/performance, will want as much width in the suspension plan/as wide of a track as possible as it generally gives more stability to the vehicle. So they want the suspension etc as wide out as possible without compromising the wheel sizes or making it look like a squashed bit of cheese.

That's my take on it anyway.
cowlover, Sep 24, 2:36am
AFAIK its all to do with steering geometry and the need to get the centre point of the tread at the pivot point of the wheel.Was simple in the days of Kingpins and large diamater wheels but frontwheel drive and CVs etc caused the need for more offset and as we saw in the other thread the likes of the Austin Maxi almost ended up with the wheel centre outside the tread.Similar situation applies with trucks and vans too.I remember a Maxi running about in the 70's with a set of mags with conventional rear wheel type ofset.Not only did it look stupid it handled like a Land Rover with a flat tyre
00quattro00, Sep 24, 4:12am
You would not beleive the amount of idiots that state the offset as rwd or fwd offset when you ask for the actual offset
rsr72, Sep 24, 6:09am
Offset- the measured distance from the inside face of the centre out to the edge of the inner rim.
morrisman1, Sep 24, 6:20am
no, it is the distance between the mounting face and the mid point of the wheel (between edge to edge). 0mm offset, the mounting face is exactly half way between two edges of the rim.
rsr72, Sep 24, 6:33am
#9- Yes, you're quite correct.
I've always used the backspacing, centre to the rim measurement, which has also been called the offset (although not technically correct) before frt-wheel dr. became dominant.
skin1235, Sep 24, 8:00am
imo this is closest to the design intent, getting as much weight centered on the critical pivot point as possible also meant the bearings and hub assembly could be lighter yet stronger
the drum brakes of old were a lot narrower than the hub mounted disk we use today, the pivot point extension ( king pin inclination) put the point almost center of the tyre on the road surface ( incidentally this promoted understeer inherent)
current deeper rims allow a longer hub due to cv joints, and disk mounting methods to still suit the optimum positioning of that pivot point, albeit moved slightly further inboard to alleviate that inherent understeer)
esprit, Sep 24, 8:48pm
The reason FWD offsets are typically larger on FWD cars centers around trying to get the contact patch as close as possible to the steering pivot axis for each upright. This is a lot better to prevent things like torque steer and steering grab when trying to feed power through the same wheels that are currently doing the steering.
mrfxit, Sep 24, 10:04pm
IN THE BEGINNING . Yea nah but probably is. .

When small bodied FWD's were 1st being designed,they crated deep dish wheels to allow as much driveshaft & suspension arm length as possible while still allowing a reasonable amount of tire width plus keeping as much as possible within the wheel arch body.
The longer the driveshaft & suspension arms are on a fwd, the less the total top/bottom inclination angle equaled less stress on the cv's & smoother road ride due to more suspension travel being available.
The majority of wheels being made these days factory & particularly aftermarket rims, now have a very deep dish where the center of the rim is WAY OFF center to the stud mounting face (mostly right out to the outside face rather then center or inboard.)

Pretty much anything apart from shopping basket cars these days will have deep inside disk mags on it.
Namesome (even mild)performance turbo/v6/ v8 /supercharged/ inline 6cyl cars made in the last 5 years that has a factory rim with the TRUE center of the rim anything like close to the stud face either side
mrfxit, Sep 24, 10:06pm
Think about it .

Whats siting between the front legs of a RWD compared to a FWD
bill-robinson, Sep 25, 4:45pm
Thanks people, I have gathered some info from this.
supernova2, Sep 26, 6:40am
I don't know.I can tell you what's between the front legs of a FWD compared to a RWD but not the other way round.As I see it everything between the front legs of a RWD is also in a FWD.
bill-robinson, Sep 26, 3:12pm
Well that helped the discussion
mrfxit, Sep 26, 5:58pm
LOL ummm better take a fresh lesson or 2 in basic FWD verses RWD construction
splinter67, Oct 21, 9:40pm
For magicmat and hes only been back once since then
matarautrader, Oct 21, 10:18pm
I asked my wife if she was FWD or RWD. Should have waited until she put the pot down!
supernova2, Oct 21, 11:23pm
Ok so whats inthe RWD that is not in the FWD!
splinter67, Oct 21, 11:54pm
someone cool in the drivers seat
joanie32, Oct 22, 12:11am
google scrub radius/ scrub angle to find the truth.