OTK Wheel Nut

Every site says the wheel nut on my MXJ Wheels are M8, but the head is a 10mm socket. Might be a stupid question but which measurement do I use when I buy new wheel nuts?

M8 is a reference to the thread diameter, not the nut size. Nut size is measured across the flats

I would also be careful buying wheel nuts other than OTK. I have had bad luck with “off brand” wheel nuts backing the studs out of the hubs. For whatever reason, the OTK wheel nuts seem to be more use friendly with the threads on the OTK hubs. YMMV

1 Like

do you know why the nuts round so easily? i use an m12 impact on the 1st setting and still occasionally damage the corners of the nut.

Lousy socket. Snap-On are best but Autozone Duralast are almost as good.


I’d wager the impact driver is a problem. It’s a brute force tool. I hand tighten the nuts.

The OTK wheel nuts are self locking, however after a while they lose that capability. If you impact them new you pretty much guarantee the stud will strip and back out.

In fact just last week I replaced all my front spindle studs because they were stripped from using an impact (half of them just came out with the nut in them).

The problem is that an Impact makes it much quicker and easier especially when in a time crunch. I buy non locking ones from Fastech and they are a breeze and don’t round out very much because the socket isn’t fighting the locking part of the nut to tighten.

I also recommend titanium studs over regular steel ones, they are much more expensive but last much longer and don’t tend to strip or warp under immense pressure.

The problem is those nasty copper plated ‘k’ nuts. ’ Intended for once only use in high temperature situations’. I assume there must be some good reason not to use a standard M8 Nyloc nut, either with a washer or flanged, tightened by hand with a six point 13mm socket with a dedicated torque arm?

I use impact for taking them off and putting them on loosely (I stop before it starts to actually chug). Then finish off hand-tightening with ratchet. 80% of the speed benefit of the impact with very low risk to wheel studs / lugs.

1 Like

I switched to barrel nuts last season and love them! No issues with damaging the studs.


If you use a 12pt socket you’ll be sure to round them very fast. If you use a 6pt socket they should last awhile. In regards to the locking style little nuts, if you use just a bit of oil or anti-seize it can help keep them from seizing and pulling out the studs. That’s only really when they’re brand new, after they work in a bit they’re fine.

1 Like

Yeah I cannot find an answer and I quite frankly don’t want to be the test dummy on if a wheel nut will hold a wheel on at 70mph. I wish I knew because its a hassle for me to go and order 12 new copper nuts for $10 shipping.

1 Like

You can use Nylocks. I’ve used them before. There are some wheels that can only fit the OTK style or barrel nuts, tho.

I’m currently using normal flanged non-locking nuts from McMaster.

1 Like

We impact hundreds of nuts on and off every week and have no issues.

Only use the OTK crimped nuts at this point - the off brand ones are junk. The Freeline ones used to be great and may still be though.

Only use a quality six point socket.

A dab of WD on first use fixes 90% of the problems.

We’ve gone from replacing a dozen studs a week to one or two a month for customers. A little instruction and the proper hardware have helped tremendously.


@KartwerksDan how many times do you trust the nuts?

Does anyone else have experience with the titanium studs? I’m a little paranoid, had some issues with the studs and nuts on a flat kart. I also like the cool factor.

Until they start to deform, we keep using them. And that usually only happens when someone uses a 12 point socket on them. Easily a season though if treated well.

1 Like

Yesterday morning I was reading through this post. I had a night race that evening, so I wasn’t due at the track until later in the afternoon. There I was, enjoying my morning coffee considering all of the comments put forth and looking back on my own personal experience with the OTK lug nuts. Now thus far, I had only had one incident with a nut rounding off and used narrow chisel and hammer to break it loose. It was a hassle, 20 minutes later it came loose and within minutes I was able to find a replacement in the paddock to back in business. I always pack spares now and change them when I notice the corners starting to round. Fast forward a year or so later and I am out on a practice day. First session out, I get this weird vibration on the straights. It felt like I had a bent axle or something. I bring it in and put it on the stand and start checking things over. Come to find out, one of the studs on the engine-side rear broke off. How in the hell did that happen? I had done all of my pre-run checks! It broke below the face of the hub, so this was not going to be a trackside fix. Luckily I had my short hubs with me and just swapped them out. Keep in mind this was late winter/early spring. Since then, I have put two race days on them without incident. During my final of my last club race I dropped a wheel out of the chicane halfway through the final ending my race. Tired from the day, I zipped tied the chain to the axle and loaded up everything to deal with it at home. Also worried I bend the sprocket and/damage the chain, I ordered replacements.

Now back to the somewhat present. Before loading up the kart for last nights race, I go to swap the sprocket and chain. As I am taking the relatively new lug nuts off of the hub, not one, but two of the studs back out. Well that wasn’t expected! I spend the next hour and half trying to get the lug nuts off of the studs. I tried double nutting them, using a vice to hold them, heating the brass nuts, penetrants, but nothing worked. Finally I pulled out the hub with the single broken stud and extracted the two seemingly undamaged ones and installed them in my current hub. It took less than 10 minutes. At the time, I thought it was a strange coincidence that I was dealing with an issue that I had read about earlier that morning. Anyway…Off to the races!!

Has anyone else experienced something similar before?

;Just some side notes. I only use OTK lug nuts. The hub in question is only a season or two old and rarely used compared to the standard hubs that had a stud break on. The lug nuts had only been on/off 2 or 3 times. I always hand start the lug nuts, but using and impact to first run them down, then blip then once or twice and never hold down the trigger for more than a split second. The lug nuts backed off to the end of the stud so that they were nearly flush. I do not use any spray on anti-seize on the studs as Dan mentioned above. Maybe that was my issue, but it hasn’t been an issue in the past.

I welcome any thoughts on this matter.

1 Like

All the time. In fact I’ve come to expect it, I don’t know if I’m doing something wrong or what. I bought a pack of 100 M8 non lock nuts to double nut to install/remove the studs. I switched to titanium ones as well and they have worked much better. I impact them on slowly but it still happens. It’s also pretty much impossible in my experience to remove the nut from the stud when it backs out of the hub. In my experience though I find that the nut welds itself to the stud hence causing the stud to back out, I am also going to try anti sieze next time.

That’s the thing, I have used the same procedure for years and never backed out a stud before. I am wondering if I just got a few bad lug nuts that had the tolerances on the locking side of the nut a little too tight that they seized on the stud.