Author Topic: Offset Calculator (Read 4367 times)

Yogi · « **on:** January 15, 2011, 02:32:37 PM »

I was playing with this calculator:
http://www.1010tires.com/WheelOffsetCalculator.asp posted by Kelu in another thread.

I input 8" 55mm for the old wheel and 8" 40mm for the new wheel. According to the calculator, reducing the offset by 15mm will make the wheel 15mm further AWAY from the strut, and 15mm CLOSER to the fender! This seems the opposite of what is shown in their drawing! IOW, the wheel should be closer to the strut and further away from the fender as I see it.

What am I missing?

Arabas · « **Reply #1 on:** January 15, 2011, 03:04:45 PM »

the smaller the number of the offset, the closer the wheel to the fender (the more it sticks out)

Kelu · « **Reply #2 on:** January 15, 2011, 03:05:46 PM »

Quote from: Yogi on January 15, 2011, 02:32:37 PM

According to the calculator, reducing the offset by 15mm will make the wheel 15mm further AWAY from the strut, and 15mm CLOSER to the fender!

That is correct, that image I think is deceptive too.

Yogi · « **Reply #3 on:** January 15, 2011, 03:07:59 PM »

Quote from: Kelu on January 15, 2011, 03:05:46 PM

That is correct, that image I think is deceptive too.

OK, so the drawing in the calculator is wrong?

Arabas · « **Reply #4 on:** January 15, 2011, 03:38:26 PM »

the drawing and the info it gives are correct.
yogi? have you been drinking with GJ?

Yogi · « **Reply #5 on:** January 15, 2011, 03:58:27 PM »

I quit drinking 16 yrs. ago!

I just tried the calculator again and I don't get it! If you reduce the offset 15mm in the drawing, then the wheel will be 15mm CLOSER on the inside and 15mm FARTHER AWAY from the outside (fender), but the captions in the calculator say the opposite! WTF??

Arabas · « **Reply #6 on:** January 15, 2011, 04:20:45 PM »

sorry Yogi, i was just joking...

try this, it is much more clear

http://www.willtheyfit.com/

idkfa · « **Reply #7 on:** January 15, 2011, 04:58:37 PM »

Yogi, what wheels have you found in our bolt pattern with such an offset?

Yogi · « **Reply #8 on:** January 15, 2011, 05:31:58 PM »

Quote from: Arabas on January 15, 2011, 04:20:45 PM

sorry Yogi, i was just joking...

try this, it is much more clear

http://www.willtheyfit.com/

No harm, Arabas! I knew you were joking!

Thanks for the new calculator. It shows what the other says so the drawing in the 1010tires.com calculator must be wrong.

Yogi · « **Reply #9 on:** January 15, 2011, 05:34:32 PM »

Quote from: idkfa on January 15, 2011, 04:58:37 PM

Yogi, what wheels have you found in our bolt pattern with such an offset?

It's been a while since I saw the wheels with a 40mm offset. I can't recall where they were. I was mainly just trying out the calculator to get an idea of how a smaller offset moves the tire/wheel.

Arabas · « **Reply #10 on:** January 16, 2011, 07:08:09 AM »

Yogi, the drawing on the 1010tires is not wrong (according to this source http://en.wikipedia.org/wiki/Offset_(wheel) )

the problem is that it is a bit more complicated than a simple drawing.
if you imaginery place in this drawing the axle to fit right after the orange line as a steady thing, you will see that when the offset gets smaller, the whole wheel (apart from the hub mounting surface which will not be removed because it gets connected to the wheel) will be moved to the right, so the drawing and what it says are in accordance.

just look at the drawing and imaginery place it on the whole picture of the car

Yogi · « **Reply #11 on:** January 16, 2011, 02:17:53 PM »

Now I get it, Arabas! The orange line is stationary and the dotted line moves. I was looking at it the other way around - DOH!

Thanks for helping me to understand!

Arabas · « **Reply #12 on:** January 16, 2011, 03:04:17 PM »

Glad i could help Yogi!

Dave@DDMworks · « **Reply #13 on:** January 16, 2011, 03:47:20 PM »

Also hopefully not to confuse everyone more, remember that there is positive and negative offset. Not sure if anyone has covered this, but offset is the measurement from the center of the rim. So if the mounting surface was exactly at the center of the rim it would have a 0 offset. As you move the mounting surface towards the side of the rim facing outward you measure that distance in mm and call it positive offset. If you move the mounting surface from the center of the rim closer to the inside of the rim you measure the distance again in mm, but call it negative offset. Although most of the times positive offset wheels are all you are going to commonly find, because negative offset rims really push the tires way out, and also do some really not so great things to steering in the front, unless the car was designed for them.

Arabas · « **Reply #14 on:** January 16, 2011, 04:27:38 PM »

thx for adding that Dave!
i put on my 79 manta 13X8 wheels with -12mm offest, old school style!

from http://www.kappaperformance.com/forum/index.php/topic,4737.20.html

Sly Bob · « **Reply #15 on:** January 29, 2011, 04:57:57 AM »

Found another wheel and tire calculator tonight that lets you play with tire and wheel sizes. It's interactive and seems to work really well.

http://www.rimsntires.com/specs.jsp

Yogi · « **Reply #16 on:** January 29, 2011, 08:56:54 AM »

That's a good one, Bob!

Thanks!

Yogi

Kelu · « **Reply #17 on:** January 29, 2011, 09:04:39 AM »

GREAT LINK!!! Bob, many thanks for sharing

Sly Bob · « **Reply #18 on:** January 29, 2011, 04:09:13 PM »

Yeah someone put a lot of time into setting that calculator up.

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Author Topic: Offset Calculator (Read 4367 times)