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Old 02-09-2012, 10:29 PM   #1
SUX2BU
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FREE wheel offsets!

If you have searched for custom wheels you have probably gotten stuck on the magical offset. You the right wheel offset that won't stick out AND won't rub on the inside. But almost every custom wheel mfg doesn't like to share their offsets, with good reason. It takes work to figure out exactly what fits and what doesn't.

This is where I come in. I'm not revealing anyone's secret offsets, instead I did my own measuring and will post my results. REMEMBER this doesn't mean you can take any wheel apply these offsets and it will fit. You have to make sure the inside face of the wheel clears the brakes.

I took all four of my wheels off today to give my brakes, fender wells and wheels a good cleaning. Well, I have been thinking about stepping up my front 18x8.5 wheels to 18x10 wheels. Since I had my wheels off I decided to do some measuring and figure out the offset I would need if/when I swap up.

My current set up is Forgestar F14s in textured black. 18x8.5 semi concave fronts and 18x11 rears. I got the semi concave 18x8.5 because I wanted the narrowest F14 for the least rolling resistance and lightest front wheel. I picked a 35mm offset for the front because a stock front wheel is 20x8 with 35mm offset. So with the same offset and 1/2" wider, the 18x8.5 will be 1/4" wider than stock on inside and another 1/4" wider on the outside. After setting up my CTS-V spares as skinnies for the track (http://www.camaro5.com/forums/showthread.php?t=181059) I left the 12mm spacers on with mt F14s just to try it out and I like the more aggressive, flush with the fender look better. So if I were to do it again I would get the 18x8.5 wheels with a 23 mm offset but this size F14 only goes as low as 26mm offset.

On the rear I looked up a bunch of other 11" wheels that did have the offsets available, even though they weren't 18s, and did a lot of measuring. I crossed my fingers and ordered 18x11 deep concave 48mm offset. It came out great! The perfect mix of flush with the fender and plenty of clearance inside! The only downside is you have to clearance the LCA for lowered cars like the Weld 17" wheels.


Next up is the 18x10 on front.
I used one of my deep concave 18x11 48mm F14s on the front to figure out the best offset. I did a lot of trial/error and came up with a small problem. The very top tip of the aluminum spindle was contacting the wheel and I still wanted it to go in more. So I'm gonna give you 2 offsets, one is what I will run since I don't mind grinding down the spindle (you will also use this one for any wheel larger than 18 since they won't contact the spindle) and the other is what you would run if you DON"T want to grind your spindle. Making parts fit is just a part of hot rodding and the section of the part I ground down is not a structurally important part of the spindle. I also included a few pics of these since these are the measurements I was most after.

If you don't mind grinding a little 18x10 on front will require a 38mm offset with a narrow tire and less offset with a wider tire. This is what I will order if I ever go 18x10 up front. 19" wheels and higher clear the spindle just fine. BUT if you do run the 38mm offset I wouldn't run a super wide tire because they will flex more and may rub the sock on hard turns. If you Do want to run a wider tire just back off on the offset.

If you DO NOT want to grind the spindle the 18x10 up front will need a 24mm offset. This (or very close to it) is probably the offset that comes on the front 18x10 Whiteside Customs wheel. This wide a 18" wheel with this low off an offset sticks out just a little and so I would much rather grind the spindle a little and make it sit flush with the fender.


So here are SUX2BU's recommended offsets
Front (these are all with stock shocks)
18x8.5 23mm (up to 35mm is ok also, just a little more tucked)
18x9 29mm (no more than 37mm if you don't want to grind spindle, up to 41 if you do)
18x9.5 36mm if you want to grind (30mm if you don't want to grind)
18x10 38mm with a narrow tire if you want to grind (24mm if you don't want to grind)

Rear
18x11 48mm (you have to clearance the LCA on lowered cars)
18x10.5 42mm (up to 53mm and you might have to clearance LCA on lowered cars)
18x10 35mm (up to 50mm)
18x9.5 29mm (up to 44mm)
18x9 23mm (up to 38mm)

The first two pics are the spindle I ground simulating 18x10 w/38mm and the last two are not ground simulating 18x10 w/24mm.
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Last edited by SUX2BU; 03-12-2012 at 07:27 PM.
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Old 02-10-2012, 02:04 AM   #2
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Exactly what I am looking for. Thank you for doing it. 18x10 38mm doesn't leave much room for tire. I am curious what you are planning to run.
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Old 02-10-2012, 04:15 AM   #3
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Great job and thanks for the time & info!

I'm looking at those wheels but in a 19x10 all around with a 275/40. What would you recommend for an offset that will work on both the front and the rear?

I've always liked where the rear tire sits in the wheel well, but the fronts are too far in for my taste…

BTW, I like what you've done here. If I have to space the fronts to keep the rears where they are now (same offset all around), I'm fine with that...
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Old 02-10-2012, 08:53 AM   #4
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Quote:
Originally Posted by SUX2BU View Post
REMEMBER this doesn't mean you can take any wheel apply these offsets and it will fit. You have to make sure the inside face of the wheel clears the brakes.
Excellent information, thanks for sharing your wealth of knowledge on the 18" wheels!!! You sorta pioneered that venture with your Forgestars. I'm very interested to see how your plans for the 18x12's work out.

And you "hit the nail on the head" with the statement I quoted above. That measurement from the face of the mounting pad to the backside of the spokes is referred to as "mounting pad height" or just simply "pad height". And you are very correct, regardless of the offset, if the wheel is not designed with a fairly high pad height, it won't clear the SS Brembo calipers. Compared to the thousands of different wheel designs available, there are really only a handful of wheels that are designed with purpose in mind. The Weld RT-S wheels pride themselves for having 3 different pad height designs: low, medium, high. And of course, the SS requires the high pad.
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Old 02-10-2012, 10:24 AM   #5
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I heard most guys run +25 front and +40 rears for 20" rims. Not sure if there is any truth to this.
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Old 02-10-2012, 11:53 AM   #6
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Here is a website I use a lot when dealing with offsets. http://www.1010tires.com/wheeloffsetcalculator.asp

Quote:
Originally Posted by Sleepy View Post
Exactly what I am looking for. Thank you for doing it. 18x10 38mm doesn't leave much room for tire. I am curious what you are planning to run.
Yeah, it's a tight fit so I would not run the widest tire that will fit on the rim. First I will see if my BFG G-force KDW 335/30 18 fit in the rear. If they do and I do decide to go up to an 18x10 up front I would run a matching BFG G-Force KDW 275/40 18 at 26.7" tall with the 38mm offset or 295/35 18 at 26.1" tall with something like a 32mm offset.
Quote:
Originally Posted by Parabolica View Post
Great job and thanks for the time & info!

I'm looking at those wheels but in a 19x10 all around with a 275/40. What would you recommend for an offset that will work on both the front and the rear?

I've always liked where the rear tire sits in the wheel well, but the fronts are too far in for my taste…

BTW, I like what you've done here. If I have to space the fronts to keep the rears where they are now (same offset all around), I'm fine with that...
The 19x10 38mm would be PERFECT on front and rear if you run that narrow tire, anything wider and I would do a lower offset up front.
Quote:
Originally Posted by blazzin1 View Post
Excellent information, thanks for sharing your wealth of knowledge on the 18" wheels!!! You sorta pioneered that venture with your Forgestars. I'm very interested to see how your plans for the 18x12's work out.
It all depends on how well my 335/30 tires fit under Ginger on the 11" wheel.
Quote:
Originally Posted by Nessal View Post
I heard most guys run +25 front and +40 rears for 20" rims. Not sure if there is any truth to this.
Offsets mean nothing with out knowing the width of the wheel. remember offset is how far off the middle the mounting pad is, if you don't know the width, you don't know the middle. People used to use backspacing instead of offset, I don't know why they switched, backspacing is easier for people to understand.

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Originally Posted by CC Performance View Post
I've never heard of a wheel MFG hiding offset information, its basic information to the wheel itself. If they don't share that info then move on. My guess is if it isn't posted then you will make the mistake of buying and using it as is..... they sell more that way and most of those are universal and don't care which car its going on.
Comes down to the end user and if they are smart enough to know the difference.

What are the factory offsets is a good place to start. You can then know exactly what will work and wont simply by doing the math and using a measuring stick or tape
I'm not talking about wheel regular mfg like TSW, BBS or any other regular wheel mfg. I mean the custom wheel guys where you can pick your own offset. Forgeline, CCW, Forgestar, Whiteside Customs (I think these only come in one offset, but they still won't release them), ect.

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Old 02-10-2012, 12:01 PM   #7
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Thanks a bunch!!!

I've been going crazy with wheel and tire numbers the last couple of days.

This was a big help!
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Old 02-10-2012, 12:13 PM   #8
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Awesome! Thank you. I had a Honda S2000 and I installed a used set of 17x7.5" 6 split spoke wheels all the way around with 225 tires. However on the front I couldn't even fit a sheet of paper between the brake calipers and the wheel spokes because the wheels were built with an offset for a 96-99 Mitsubishi Eclipse. With a 1/4" spacer the tires would rub when I turned. It's great to find these things out before buying wheels. Thanks again.
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Old 02-12-2012, 09:35 PM   #9
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Old 02-13-2012, 08:52 PM   #10
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Quote:
Originally Posted by blazzin1 View Post
You sorta pioneered that venture with your Forgestars.
I get no love for doing it first...and second, and third, and...

Good post SUX2BU. Those will work for stock struts. Pfadt/KW coil-overs require more clearance.

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Old 02-13-2012, 10:14 PM   #11
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I get no love for doing it first...and second, and third, and...

Good post SUX2BU. Those will work for stock struts. Pfadt/KW coil-overs require more clearance.

Tony
Yeah, I never would have gotten these wheels if it wasn't for this thread: http://www.camaro5.com/forums/showthread.php?t=125456

Yup, if anyone wants to send me some coil overs I'll be happy to do the same for those.

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Old 02-17-2012, 06:10 AM   #12
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So what do you guys think of this
Front +25mm offset 20x9 245/40/20
Rear +25mm offset 20x10.5 275/35/20
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Old 02-17-2012, 12:39 PM   #13
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So what do you guys think of this
Front +25mm offset 20x9 245/40/20
Rear +25mm offset 20x10.5 275/35/20
Front wheel is good, rear wheel will stick out. Both tires are too narrow for the wheels.
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Old 03-16-2012, 12:35 AM   #14
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I ordered wheels from Asanti/Lexani brand Kinesis K118 22" 9 front 10 rear, I wanted 11" but the seller said he'd recommend 10",
Carbon Fiber face outlined in gloss black, gloss black power coating lips Satin barrels...Satin black power coated rivets inside and out(Bolts)....all cleared...!
Step up for larger lips 3 and 5" for my 2010 2SS with HR sport springs.......here is what their sending me,
Fronts...Center Bore=67.1 Offset=30
Rears....Center Bore=72.56 Offset=35
I wont them to fit perfect in regards to Break clearance and that they don't stick and or do fill up the wheel wells........
I would like to run 265x35x22 and 305x30x22 tires what do you guys think?
I'm 2 weeks into the order and was told they would be ready to ship in 4 weeks...!
Thanks.
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