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Large Slip-On Wheel Spacers on Track

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I know the topic of wheel spacers has been well-covered on various forums over the years...but I haven't seen a good enough one here yet 😄

My question boils down to, is there a theoretical limit to how much slip-on spacer one can/should use in a performance environment so long as the studs are long enough and sufficient torque is applied to the lugnuts?

Background: 1995 Mustang GT used for track and autocross. Currently running 18x11 Hypergrams and 315/30/18 Falken RT615K+. Going to 315/30/18 Yok A052 for autocross and used 305/680/18 Michelin/Pirelli slicks for the track. I don't want to be trying to switch tires on/off wheels before track days, so I want another set of wheels. I was going to just get another set of 18x11 Hypergrams until I saw that Konig came out with some new wheels called Heliograms in 18x12. They're a +20mm offset. My current Hypergrams in 18x11 are +15mm offset. To get roughly the same backspacing as my current wheels (which are about as close to the coilover sleeve as I can run), I would need to use a 3/4" (possibly even slightly more) wheel spacer. That also begs the question of whether it's safe to stack wheel spacers to get the best possible spacing (like a 3/4" hubcentric with another 1/8 or 1/4" spacer, for example).

I think I have enough wheel stud (3.5" underhead length ARP studs). Maximum Motorsports makes slip-on spacers up to 3/4", so my takeaway is that they consider them safe enough up to 3/4" (or maybe there's not enough market for larger, I dunno). They also make great points about the CF between the hub being the primary holding factor for the wheels. I just want to be sure about the general idea of using a spacer or combination of spacers that large in a track/slicks environment before I drop $400 on a wheel to test out fitment.


Heliogram.JPG
 

TMSBOSS

Spending my pension on car parts and track fees.
7,530
5,247
Exp. Type
HPDE
Exp. Level
10-20 Years
Illinois
As long as the spacers are hub centric and the studs are holding the wheel and not a spacer with its own studs, you should be good. I have three sets of 25mm spacers and run them on my Boss and 350 without issues.

OP Mustang has a good assortment of spacers. Check them out. They are showing light weight hub centric spacers from 10mm to 35 mm. Most are in stock.
 
For the price your are paying you should be able to get some hub centric wheels from Apex --- have you checked them out also?

I had a note at the bottom of the original post that said, "Before anyone messes with me about running these unproven wheels instead of Apex or the like...they don't have anything for SN95. Everything I have found 18x12 is even more offset for later cars."

I erased it right before I hit the post button lol.
 
98
143
Exp. Type
Autocross
Exp. Level
20+ Years
Olsburg, KS
As others have said, a 25mm spacer is pretty common. I run them on my 2018 and will run them on my 08 once I get the suspension set up correctly. I would shy away from using multiple spacers. It's just that much more to go wrong. It introduces another area where dirt and debris can affect how well things are clamped, along with another layer of machining tolerance stackup.
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
Use 25mm spacers all the time. Have been using the ones from OPmustang.com for a while now and have put them on a number of cars with zero problems.. As long as they are hubcentric and with good, long enough studs its a no brainer... Same thing does not go for the ones with the studs mounted in the spacer. Those crack and fail all the time.
 

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