Confused about cadet tire sizes in the US

Hi everyone! We are fairly new to the sports. I have two boys in cadet - 11 and 9-years old. I am their mechanic (unfortunately not a very good one! hahaha).

They have been racing in Thailand until recently. We moved back to the United States two months ago. We entered the boys in a Rotax Max Challenge using rental karts. Back in Thailand for cadet we were using 110mm tire width front and 140mm rear. If using MG tires, they were using MG SC Red. At the Rotax event in the US, they were using MG SH Red 10x4.6-5 for ALL FOUR tires (because of the shortage of Mojo tires). I did not pay attention to which wheels they were using.

Now that the boys received their own karts, the karts came with the expected 110mm front and 140mm rear wheels. I am wondering if I can mount the MG SH tires that I have left from the event for practice. Which tires are being used in the cadet class in the US? I asked someone who has been racing here and he said 130mm front and 150mm rear. Is that correct? I’m so confused of which tires to get and which wheels I will need to use. I would like to stay practicing with the 110/140mm combinations because I know that is the regulation for Asia and Europe. But I also would like to get them racing in the US as well for practice.

Thank you!

Most (maybe all?) cadet classes in the US use 10x4.6-5 tires on all four. You can practice using the 110/140 wheels and it wont hurt anything. 130mm (an all four corners) is by far the most common size for cadets in the US (In fairness, I dont pay attention to cadet wheel sizes all that much). I dont even think I have seen 150mm wheels, but again, I dont pay that much attention. We use 130mm all the way around on my son’s kart.

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Thank you much, Derek. Sorry, just to be clear, you are saying I can use those tires mounted on the 110/140 wheels without any problem? Which wheel size are you using for the races here? Perhaps, I will get another set of wheels for racing in the US - I just want to make sure I get the right size. I know in Thailand we made sure we had a set of aluminum wheels and magnesium wheels for hotter days. I looked around but cannot seem to find magnesium cadet wheels here. Is it because it doesn’t get very hot here? Or knowing what I know now, maybe I was looking for the wrong size!

Derek is right. 130/130 is what is used for cadet racing in the USA.

As the AMV wheel importer, 95% of what I sell to cadet folks is 130/130. For extraordinary situations, some use 140mm wheels but that is it.

FWIW, the AMV Cadet wheel used in Euro comes in 110 front and 140 or 145 rear.

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When we ran cadet, we had 130mm on the front, and would switch between 130mm and 132mm in the rear. There are magnesium wheels in the 130mm size in the US. You can find them at Accelerationkarting.com or cometkartsales.com, among other stores.

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Thank you. I will look for those wheels for the races here.

Awesome! Thank you for the info.