Are MXC wheels worth the money?

For $600 a set of the AMV might as well try to find the real thing imo.

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I have to buy parts from Germany from time to time to get Motorsport parts from the manufacturer.

In my experience you will be getting a bill in the next couple weeks for import duties.

You will still be ahead of getting from a US vendor but not by as much as you think you are now.

If you’re running forged / complex-shaped magnesium wheels for additional stiffness, would you be better off with an aluminum wheel of the same wall thickness and 150% of the Young’s modulus?

Aluminum wheels are usually used as rain wheels because they heat up super quick. Not sure aluminum wheels are used for much else. Am not sure tho.

So if people are saying the MXL has “more grip” than the MXC, does that mean that it will make the kart tighter, or that it will plant the outside rear better while staying free? The difference between those two things is super important. If they do make it tighter, is it worth trying to tune around it instead of just using the MXC?

MXL and MXC are free off the turn. i.e less rear (traction) grip. Remember when talking about a track gripping up we are always talking about too much rear traction grip. Not side bite. MXL/MXC are causing the rear inside wheel to unload quicker and stay unloaded longer. I dont know whether that is because they are stiffer or less stiff. I could argue both ways. Would love to get some 3d models of the rims and analyse with my FEA software.

Also don’t get confused the MXL and MXC are different rims and there will be situations were one is a better choice than the other.

Video explains OTK wheels.

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Funnily enough the MXL havnt been that popular here in NZ. Most prefer and use the MXC still.

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That video was bomb. Bonus point for him not going into the hype about wheel “flex”.

I’ve yet to see anything to substantiate that wheels flex. As soon as I do, I’ll change my mind.

It’s mostly heat dissipation and volume. Followed lastly by the damping qualities of “magnesium” alloy vs aluminum.

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If these wheels flex, it’s where the web of the flange/hub meets the outer circumference. A thicker and webbed flange would flex less… But I have to think that the spindle and the sidewall both flex enough that any rim flex is imperceptible… I, too, would love to see some FEA done for a more definitive answer. I can’t imagine they flex much at all or they’d fail and break out after a number of cycles…

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James, I’m with you on the flex. We need to stop talking about flex. In the 50mm era, flex is almost immeasurable. I think dampening is more prevalent. Think about how much the tyre deflects. Is a 1mm (and that would be super generous) of flex going to change slip angles and jacking?

AMV is available from Italian Motors, in stock. Nice hubs too.

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super interesting discussion.

for a lower powered cr80 shifter racing on hard evinco blue tires on lower grip tracks, primarily in 85-90*+F type ambient heat (ie; hot!) , which OTK rims would you recommend? the MXC or the MXJ?

seems weird that everyone loves the MXC rims but the OTK 401r shifter chassis from with the MXJ from the factory.?

The MXC is going to keep the tire in the operating temp window better in any heat, especially if it’s warmer out.

I think a common misconception is that MXC wheels and similar forged mag wheels “reduce grip”, when that’s not really true. They run cooler and keep the tire from overheating. So any situation where the tire might get overworked, the MXC will help.

All OTK products ship with the cheaper MXJ wheel from the factory. The MXC is considered an upgrade or add-on.

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thanks TJ, super helpful (and love your youtube channel!)

so just to make sure I understand what is going on here, the MXC stabilizes the tires operating temperature better because it conducts the thermal energy out of the tire and into the rim better than the alternatives, do i have that right?

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Granted I bought MXL’s not MXC’s but I’ve only found the forged rims good for longer races and gripper tracks.

Our home track is low grip, we run pretty hard tires that notoriously take awhile to come in AND we run short races (10-12 laps @ 40 seconds a lap) and I’ve yet to run a like for like test where the forged wheels are quicker than the standard MXJ.

Now in those test, best lap to best lap is pretty much a draw, but even starting on higher pressure for the forged wheels I can’t get them to come in quick enough to be effective.

Thanks Andy, so if I’m understanding you correctly it sounds like you run the MXJ then on race day since the MXL/MXC don’t come in fast enough to work well? but fastest lap vs fastest lap are basically the same…decisions decisions…

@Andy_Kutscher you’re running KA correct? I would venture to guess in a shifter, on an Evinco Blue, you’re going to want something to keep the tires cooler with all that power. Seems like it would be quite easy to burn off the rear tires. KA at a club race with low grip and short races you can get away with the MXJ.

On a hot track with high horsepower applications I would still recommend the MXCs, to at least test them. They are a big investment though.

Try the MXJ and see if it overheats the tire. If it does, then you’ll know you might benefit from the Cs.

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@tjkoyen Yes, I run KA, we run Hoosier R60B, relatively low grip track, finals are either 10 or 12 laps on a 30-40 second track AND we don’t do a warmup lap and don’t allow tire scrubbing to build heat in a tire. Straight out of the pits, around a short oval and start the race.

…of course I justify my unique case where the MXJ’s actually work better and then we have a 20 lap final this week …runs to garage to mount forged wheels instead

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