Author Topic: Wheel offset question  (Read 2748 times)

LP640

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Re: Wheel offset question
« Reply #14 on: November 18, 2013, 12:18:00 PM »
Use a set of wheels like mine. On my Murci build I have 1.5" spacers all around because the wheels are wide and have zero and negative offset.

Fuel Hostage Offroad (18x12 -44 for the rears and 18x9 -0 for the fronts) $850 for 4 rims. They are not a special order and can be ordered anytime from average wheel suppliers.  The total cost of tires was $850 as well. Spacers werre $100 and new lugs $30.



I was told these are for trucks, how did you get these to work?

76mx

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Re: Wheel offset question
« Reply #13 on: November 14, 2013, 10:44:06 PM »
Just make sure to remember that backspacing is referenced from the OVERALL width of the wheel, not the given width. This is where it gets clear as mud. Some wheels are described in backspacing and some are by offset. Almost always, but not every time, the overall of a wheel is one inch larger than the stated width. So an eight inch wheel (stated) with zero offset is the same as an eight inch wheel with a 4 1/2 backspacing. The dimension of the line through the ball joints to the ground plane in reference to the track centerline is called the scrub radius. Ideally it would be zero to 1/2 inch but suspension design restraints usually do not get it there. Anything under an inch is fine but with your spacers it is going to be much larger. Without changing the a-arms this will remain.   

SchulzeA

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Re: Wheel offset question
« Reply #12 on: November 14, 2013, 12:50:13 PM »
Lol my bad.

01Lambiero

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Re: Wheel offset question
« Reply #11 on: November 14, 2013, 10:35:01 AM »
You said that already, SchulzeA.  You said that already, SchulzeA.  Wow!  It's like deja-vu all over again.
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SchulzeA

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Re: Wheel offset question
« Reply #10 on: September 18, 2013, 05:09:54 PM »
I used this visualizer. It works great to try different wheel and tire combos along with offsets.
http://www.rimsntires.com/specs.jsp  ::toothy

01Lambiero

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Re: Wheel offset question
« Reply #9 on: September 18, 2013, 03:38:28 PM »
I hope that the following picture helps out in understanding Positive offset, Negative offset, and Back Space.  Offset is figured from half of the total wheel width.  Positive offset is measured outward from the wheel vertical centerline and Negative offset is in from the vertical centerline.  If the measurement of the backspace is greater than half of the wheel width, subtract the wheel width to get the positive offset.  If the measurement of the backspace is less than half of the wheel width, subtract the backspace dimension to get the Negative offset.  It did for me. 

Jim
« Last Edit: September 18, 2013, 03:55:11 PM by 01Lambiero »
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Murci-Me

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Re: Wheel offset question
« Reply #8 on: July 13, 2013, 11:32:12 PM »
Nice wheels! I like those!

am33r

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Re: Wheel offset question
« Reply #7 on: July 13, 2013, 01:42:29 PM »
Use a set of wheels like mine. On my Murci build I have 1.5" spacers all around because the wheels are wide and have zero and negative offset.

Fuel Hostage Offroad (18x12 -44 for the rears and 18x9 -0 for the fronts) $850 for 4 rims. They are not a special order and can be ordered anytime from average wheel suppliers.  The total cost of tires was $850 as well. Spacers werre $100 and new lugs $30.


RT

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Re: Wheel offset question
« Reply #6 on: July 13, 2013, 01:19:11 PM »
HRE custom makes their wheels to your specs.
Select one of their styles and give them your dimensions.
http://www.hrewheels.com
Open the "Wheels" section and see if there is anything that looks good to you.
(I'm using HRE Wheels but I don't get anything for referring anybody - no kickbacks here.)

RT
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SchulzeA

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Re: Wheel offset question
« Reply #5 on: July 13, 2013, 01:00:08 PM »
It doesn't get easier than this. Type in your dimensions an see the effects. Hope this helps.  ::thumbup
http://www.rimsntires.com/specs.jsp

jdinner

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Re: Wheel offset question
« Reply #4 on: July 13, 2013, 07:38:02 AM »
Here is a brief explanation of negative and positive offset. Just do your math and order the correct wheel offset.

http://www.tirerack.com/wheels/tech/techpage.jsp?techid=101&currentpage=101

madmods

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Re: Wheel offset question
« Reply #3 on: July 13, 2013, 06:56:53 AM »
Thanks  RT for your answer. I don't want to move the wheel at all. I just want to move the wheel mounting plate back with offset to knock as much inches of the spacer as I can. Spacers are a dead giveaway for me with kitcars.
I'm not going to mess around with the  suspension, the goal is to get rid of some of the spacer.
« Last Edit: July 13, 2013, 06:59:20 AM by madmods »
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RT

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Re: Wheel offset question
« Reply #2 on: July 13, 2013, 06:42:53 AM »
What is it about the spacer you don't like?  Even if you do make the spacer thinner you will still have to keep your tire location in the wheel well at the same place.  You would just be changing where the offset occurs.
The only proper way to make the suspension/wheel placement better is to widen the suspension.
The correct way to align your tire to suspension relationship is to make the vertical axis of the A-arm ball joints point to the center of the tire contact of your front tires.  The caster will place that centerline in front of the actual contact with the ground.  The more the axis is inboard from that location, which is what you have, the more the tire will travel through an arc as you steer.  That requires a lot of clearance around the tire to prevent rubbing and could give you feedback every time you hit a bump because of the leverage the tire has to the axis.  It also leverages extra force on your wheel bearings.
You probably know all this anyway but just in case you didn't or someone reading this didn't know I thought I'd recap.
Maybe you could be the first to solve this.
Consider what you are working with.  I'm not familiar with the Porsche front end but look to see if the suspension member is a unit that you might be able to widen and re-install.  Maybe you could build new, longer A-arms.  Some builders make their own when they build their complete chassis so it is possible but must be done correctly.  They are VERY important, but you know that too.
Maybe there is someone here who is capable enough to make them for you.  Sorry, not me.  LOL
Can anybody here help?
I don't blame you for not wanting spacers but the steering condition will remain unless you rework the location of the steering axis.
Good luck and keep this thread going.  I'm sure you are not the last to want this info.

RT
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madmods

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Wheel offset question
« Reply #1 on: July 13, 2013, 05:37:52 AM »
I hate these 3" spacers on my front. Since its a Porsche I can't use the wide track. I would like to at least remove an 1" from the spacer. About 20-26mm in offset.  My offset is +20 18 x 8" rim. I hate my freaking rims so they are going to be replaced.

So to remove an inch from my spacer does my positive offset increase or decrease. Assuming the rims come in +20 and +45 offset will the 45 move the mounting surface further back? I'm very cautious about f-ing with the front due to possible rubbing, plus the fuel line(front gas tank) runs through the front side wall. I don't  have a big choice of front rims so they have been discontinued. I will take whatever I can get, any bolt pattern.

« Last Edit: July 13, 2013, 06:27:38 AM by madmods »
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