MXC vs MXL

Hi Everyone
I’m looking at a set of otk rims.Is there a superiority between the MXC and MXL
Thanks

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Some good info from precious discussion here: https://forums.kartpulse.com/search?context=topic&context_id=6699&q=Mxc&skip_context=true

Quick nutshell answer for you. The L should free the kart more and it is also a low volume wheel. My understanding is that the MXQ has basically replaced the MXL but I could be wrong on this.

Here is a table on the specification of different “leading” wheels.
(Note: I am the AMV distributor for the eastern USA, I attempt to be as impartial as possible with the information that I provide on wheels)

I have never tested the MXC and the MXQ back to back but a team I know did in a big wheel test that included AMV wheels. Here is what they found:

Most free <------------------------------------------> Free but not as much

(AMV 9F)–(MXQ)---------------(AMV 3F)-(MXC)

From my own testing and information from AMV Italy, the 9F is approximately 10-15% freer, depending on track temp, than the 3F so this gives you some sense of the difference between the MXC and MXQ.

I suppose the difference between the MXC and MXL is very similar to this.

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My .02 would be to consider what tire / track you’re running and how much, if any you need to free up the kart.

I personally purchased MXL’s a couple years ago and actually think they were the WRONG wheel for me. At the time MXC’s were sold out and I was under the impression that the MXL was the replacement, I didn’t realize that they were going to continue to make the MXC and that they were just out of stock at the time.

Why is it the wrong wheel for me? At my home track we run a relatively hard tire on a relatively low grip surface that rarely rubbers up and short races that are usually in the 6-8 minute range with no warmup lap. I run the standard MXJ wheel still at most of our races except in the middle of the summer.

The only time I really run the MXL’s are when we have a really long race at our home track or when I go to places like New Castle or GoPro that do rubber up. Even at those venues though I feel like the MXC would have been the better wheel over the MXL that I have because our engine package runs on MG Red’s which are a pretty hard tire and require a little more heat / grip in my limited experience.

As Paul stated, not many teams really adapted or liked the MXL so there’s a 3rd wheel in the mix from OTK now which is the MXQ. They claim it’s the back side of an MXC combined with the rest of the MXL design…not really certain I know how to explain how they combined the two. Also not sure if all 3 are still made or if they discontinued the "L"s or what the story is.

If you’re running Tag / shifter on a really sticky tire and need to free the kart up the MXL / MXQ is likely the way to go, I do tend to see that wheel used a lot in Europe. Otherwise I think the MXC seems to be the universally accepted go-to wheel.

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Andy makes a great point about conditions at your track or the tracks you race on. Even New Castle is not super grippy – or at least it was not for the USPKS race this year.

Also if you are running a 100cc kart (less power) you might need to free the kart a bit more than a TAG which has more power to overcome grip.

As an example, our free-ist wheel, the 9F tends to do very well in this class. Lemke who seems to win a lot runs it regularly. Just another thing to consider, but honestly, I don’t think you can go wrong with the MXC as a good choice.

another tuning aspect I’m likely thinking about incorrectly, so thanks for additional feedback on that topic.

I’ve seen you say this a couple times and I’m not trying to cast doubt on you, I love the AMV wheels that come with the Merlin karts, but how do you quantify the percentage the 9F is more free than the 3F?

Also, if you do know, is there any difference in the Oxytech wheels versus the older gold ones from AMV?

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I was going to say something similar but I’d probably have come across more cynical.

Most people, including the engineers amongst us, struggle to even define “release”, so measuring release in percentage points of freedom, sounds a little fishy to me.

Should add, I’m not saying AMV wheels a bad. I wanted to get some last year but the season ended and anything Dino Chiesa runs is probably good in my book.

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From my testing, it was from feel. I asked the guys at AMV for a number and that is what they somewhat reluctantly put it at. I also had an OTK team in Canada test the wheels and this was their conclusion. Maybe it was a bit of a self-fulfilling prophecy.

From a feel perspective, the difference between 3F and Tiger is pretty big. I think anyone that has more than just some preliminary karting experience and a somewhat sensitive backside will be able to tell the difference. The difference between 3F and 9F is much smaller but noticeable for more experienced drivers. I did not try to measure this as I am not an engineer and figured I would be chasing my tail with Mychron data. I will see what I can do this year. I need to find a data guy that will know what to do.

As for the difference between OXiTECH and the older style “gold” wheels. There is no difference in performance. Heat transfer is the same. Both wheels are/were low-pressure cast and have the same porosity characteristics. OXiTECH was developed to prevent corrosion. The chromate finish that is typically used with magnesium wheels is not very durable and wears off with use.

Interesting story on OXiTECH. It was developed because AMV makes magnesium components for the Norwegian Cruise Lines karts. The salt air was corroding these components in no time – hence OXiTECH. It is more durable and is not a heat insulator like paint or clear coat that many wheels use. I believe the guys at AMV said that OXiTECH comes out of rally car magnesium production.

As for Dino Chiesa, as I understand it, he was involved in the design and testing of the 3F wheel. KR uses 69mm PCD wheels. Most karts use 58mm PCD hubs so KR wheels will not fit but AMV makes 3F in both PCDs.

So it is a noticeable difference, the number is just more of an estimation to give an idea of how much it changes.

I did notice the OXiTECH wheels are significantly harder to mount tires on than the older style ones, so I wondered if there was any difference there but I thought they were basically the same thing.

Regarding Dino Chiesa, I’m surprised but not really that they use the CRG bolt pattern. He was involved with CRG before KR, but the wheels are I think the only thing from CRG that he brought over to the KR equipment.

Straying further off topic, I found the MG Reds really don’t seem to like the 9F wheels until there’s more rubber on the track. When I was running Stars Championship Series, the 9F had a slide, or more of a rear end step-out, at the apex that went away when I put on a set of Douglas Magnesium wheels that I’ve had since like 2016. At USPKS, the 9F was definitely the better wheel to run though, although I had other problems going on that weekend.

Same exact wheel dimensionally. Possibly because rubber does not slide as well on OXiTECH as the prior chromate finish. Not sure, but I use liberal amounts of tire mounting lube to mount tires.

CRG is actually a 67mm PCD. So yet another PCD. The main one is 58mm. CRG 67mm and I believe only for the front wheels and KR is 69mm. I believe Tecno also has a 66mm optional PCD. This is frustrating for me as I can’t get the 69mm, 67mm is not worth stocking for the handful of CRGs out there.

Low grip track and low grip tire are not a good combination for 9F. If it is not too hot, the DWT is a good alternative. I use the Tiger for lower grip applications. USPKS Carolina was approximately 44 degrees F for qualifying not a friendly environment for the 3F or 9F and I did not have my Tigers with me. Next time I am bringing Tiger aluminum wheels to use for these types of conditions.

I didn’t even think about that, makes a lot of sense though.

I actually didn’t know that, I thought they used the same spacing. I do remember Tecno has their own wheel sizing. Do you know how the different sizes affect kart handling? I’ve been wondering about that for a while.

Yeah, I need to get the other sets of wheels for my setup. I have to run more to keep my driving form well, which I have not been doing a good job of these past couple years, and would like to have the proper wheels for these scenarios. I didn’t know the Tiger was aluminum though, I thought they were all Mag. Does AMV make wheels for rain racing or is that just the Tiger?

Handling difference between different PCD – I answer the question in this article but in a nutshell, not a big difference. A larger PCD wheel/hub combination will tend to be more rigid, providing more grip. FYI – The AMV 9F hub has an oversize hub diameter to provide a more rigid wheel/hub combination comparable to a larger diameter PCD.

AMV Tiger wheels – they are made in both magnesium and aluminum versions. Only the magnesium wheels have been present in North America, but I am ordering aluminum 130/180 for customers that have asked for rain wheels and I am also ordering a few sets of 212 rears to help with qualifying in 40-degree weather. It will also be interesting to see how they work at Road America which by all accounts had zero grip for the 2020 USPKS race. If it is not hot, they could work. The spoils of being the wheel guy I guess.

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By the way, I really commend your efforts to explain the differences. Most distributors/sellers just don’t bother or care.

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Thx Nik. I have felt for years that there has been a big info gap in karting. Part of the reason that I wanted to handle wheel distribution for AMV was to provide more information on some of the basics. Manufacturers and distributors have a responsibility to inform their users.

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