Help calculating offset after lip change

ok so I have some rims I'm going to rebarrel from a recommended source.   

20x8.5 +37 Hi
20x10 +49 Lo

I'm thinking I could go 20x9.5 or 20x10 up front and 20x11 or 20x11.5 in rear.   That means I have a choice to go 1" or 1.5" bigger outer lips.  Correct?

If I'm looking at this correctly the offsets should change to these:
20x9.5 +12 Hi
20x11 +24 Lo

20x10 +0 Hi
20x11.5 +12 Lo


I'm thinking about maybe doing a mix of 1.5" bigger lip front and 1" in rear.  So that being then:

20x10 +0 Hi
20x11 +24 Lo

correct

2nd'd

20's on a Y33? :(

[QUOTE=chrispy;362468]20's on a Y33? :([/QUOTE]
 
 
What's the problem w/ that?

wrong.
 
 
original:
8.5 +37
10 +49
 
+1":
9.5 +24
11 +36
 
+1.5":
10 +18
11.5 +30

[QUOTE=BLKonBLK98;362480]wrong.
 
 
original:
8.5 +37
10 +49
 
+1":
9.5 +24
11 +36
 
+1.5":
10 +18
11.5 +30[/QUOTE]

Yeah this is what I wasn't sure on...  either the 1" is going to give me 25mm more offset or half that...  I think I should draw out to scale and do some measurements.

[QUOTE=PANCAKES!;362471]What's the problem w/ that?[/QUOTE]

They just look huge. Don't get me wrong, they can still look good like your old AME's. But the 19's on your car fit so perfect! I guess 20's look huge when guys like broke and cheez are running 18's. =)

HA! Too me they're rims look waaayy too small for the car :shrug:

[QUOTE=Blitz;362485]Yeah this is what I wasn't sure on... either the 1" is going to give me 25mm more offset or half that... I think I should draw out to scale and do some measurements.[/QUOTE]
 
it's always half. if you change width 1 unit the centerline only moves .5 units, which is where offset is measrued from.

So, assuming this is a 3 piece wheel, you're only planning to change the front/outer lip of the wheel?  Leaving the back end/inner lip of the wheel alone? If so, you and mike may be taking a different approach at how to rebarell. Thus the confusion of right and wrong in this thread.

[QUOTE=BLKonBLK98;362491]it's always half. if you change width 1 unit the centerline only moves .5 units, which is where offset is measrued from.[/QUOTE]

That's what someone told me and couldn't figure it out....  Looking into it.

[QUOTE=jeebus;362510]So, assuming this is a 3 piece wheel, you're only planning to change the front/outer lip of the wheel?  Leaving the back end/inner lip of the wheel alone? If so, you and mike may be taking a different approach at how to rebarell. Thus the confusion of right and wrong in this thread.[/QUOTE]

Yes it is a 3piece and only planning on extending out the outer (front) lip and keeping the inner (usually where the sizing sticker sits) static.

I drew up something... so you see the inner doesn't change...just the outer..

[IMG]http://i285.photobucket.com/albums/ll56/tony42378/newrimsize.jpg[/IMG]

damn it's hard to see... but basically the 0 offset location changes as you add the outer lip...but the inner still stays static.   So I figure going 1.5 inch would net me around zero offset with new extended lips.

what i said still stands. the difference is .5" the amount of change when applied only to one side (lip/barrel).
 
your image is wrong because you did not move the centerline to compensate for the new width.
 
[IMG]http://i214.photobucket.com/albums/cc188/BLACKonBLACK98/ae36b158.gif[/IMG]

[QUOTE=BLKonBLK98;362528]what i said still stands. the difference is .5" the amount of change when applied only to one side (lip/barrel).
 
your image is wrong because you did not move the centerline to compensate for the new width.
 
[IMG]http://i214.photobucket.com/albums/cc188/BLACKonBLACK98/ae36b158.gif[/IMG][/QUOTE]

hmmm...  ok I get it now...   BLK thanks for the help.   Something didn't seem right.  For a sec it sounds like it makes sense but then you think again and it doesn't.   I pictured a line with X length...and got the centerline...then imagine extending one end of that line and the centerline only moves by half of the amount extended.      

Original sizing
20x8.5 +37 Hi
20x10 +49 Lo

Changing outer lips 1.5" only would net me
20x10 +18
20x11.5 +31

I think this weekend I'll test fit and double check the 20x10 +49 isn't touching anything inside my wheel well.

blk's calc r correct. a lil off compared to mine in my head but it all depends on rounding up or down on the tenths of a mm

[QUOTE=chrispy;362487]They just look huge. Don't get me wrong, they can still look good like your old AME's. But the 19's on your car fit so perfect! I guess 20's look huge when guys like broke and cheez are running 18's. =)[/QUOTE]
18's for static and no kit, and daily driver.
19's for kit and daily
20's for air and kit and bishes in the back seat!

20s bling
19s clean
18s mean

Word!!

You're adding 25mm to the outside only, correct?  And yes offset IS determined from centerline, but that would only be half if it was equally distributed to both sides of centerline.  I still don't understand your logic?

stop concentrating on the final fitment.
 
picture the relationship of the centerline to the mounting face. by adding an inch to the outer edge you only move the centerline half an inch closer to the mounting face.
 
if you were to make equal changes to the lip and barrel you would retain the original offset and only change the width.

for the sake of argument lets keep it simple, a x10 +/- 0, add an inch to the outside, changing it from 5" inside 5" outside to 5" inside and 6" outside, would be x11 -13 (an inch is 25.4 mm, divide by 2 =12.7, round up to 13). 

if you want to verify, use the 1010tires offset calculator. the center line shifts only 13 mm because the centerline for a 11 inch wide wheel is at 5.5", whereas the centerline for the 10 inch wheel is at 5".

p.s. i only know this knowledge from paying attention to the good folks here at VSC! :biggthumpup:

i use the 6, 13, 26 rule

Haha, yep I'm just looking at it fitment wise, sorry for the confusion.  It's moving out another 25mm from the mounting point.  I don't care much else than that it'd be an inch more dish.  I like dish.

I mean if you looked at the offset and said..oh it's only another 1/2"...well, it's not.  And that's what I was referring to.

[QUOTE=BLKonBLK98;362875]stop concentrating on the final fitment.
 
picture the relationship of the centerline to the mounting face. by adding an inch to the outer edge you only move the centerline half an inch closer to the mounting face.
 
if you were to make equal changes to the lip and barrel you would retain the original offset and only change the width.[/QUOTE]

BLK hope you weren't talking to me because I understand now.  Hopefully others learned too who didn't know this.  Thanks again for your help

nah, i was tryin to clear it up for mike (elpres). i think we're all on the same page now. what happened to the ssr?

[QUOTE=BLKonBLK98;362981]nah, i was tryin to clear it up for mike (elpres). i think we're all on the same page now. what happened to the ssr?[/QUOTE]

I bought my friends SSR Vienna Noble with those sizes.  I asked him first before ordering my new rims.   He said he didn't want to sell so I ordered the new rims.  Then a day or two later he contacts me wanting to sell...UGH   I have the 19" SSR SP-1 SBC still on order...  I already paid half down so I'm stuck with them.   

Today I met with the Ralph Wright....guy was straight with me and gave me the options.   I'm going the cheapest route I can....   The front face is going on the rear barrels...and that will be my front setup.   The rear setup I'm going use the front barrels and change the outers.   Turns out these wheels are 3pc but welded...so going to cost extra bucks.

yup ralph knows wassup. thats exactly what imma do wit my scaras and hes gonna do it