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Begode EX30 Heidenau K66 80/90-14


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After much research on tyres for the EX I went for a bit of a wildcard - the K66. This was on the basis that it appears to offer a good all-round tread pattern for the street and trails I do. Most tyres are a little too street or a little too off-road so the K66 is a good compromise. I found the stock CST 186 just awful – really unpredictable in most situations and tramlined too which no EUC short of a Z10 should be doing these days. And despite the CST looking almost identical to the Kenda fitted to the OG Sherman, the EX certainly didn’t ride anything like a Sherman. I wondered if the main problem was that the EX30 runs a 2.3” internal width rim. That’s wide for an EUC and far wider than even the ‘wide rimmed’ Sherman V3. This width seemed to compound the issue with the CST which has ‘for 1.85 rim’ moulded into the side wall. No wonder the CST looks stretched on the EX and as a result gives it an extremely boxy, flat profile. This can’t be ideal.

My choice was also partly due to @mrelwood praise of the K66 on other EUC’s that led me to it, and I felt that an 80/90 would be the best size to go for. The 70 would certainly be too narrow for the EX rim and a 90 has been reported as rubbing on the EX. And I certainly didn’t want to go down on the aspect ratio, partly because the EX runs little ground clearance but also because a stiff low profile MC tyre can give a noticeably harsher ride.

Removing/refitting the wheel on the EX is probably one of the easiest out there and my thanks go to the excellent YT vid from @2cells1pack for their walkthrough and as per their vid you really do need a workmate and table to make things easier. After that it’s the usual scenario of getting the old tyre off (not difficult) and getting the K66 on. Of course proper MC tyres are always more difficult to fit due to their stiffness but if you ensure that the opposite side of the tyre is always as buried into the rim as possible the whole job is made a lot easier. I see so many people struggling when fitting MC tyres if they aren’t on top of centring the bead into the rim constantly. For reference, I used zero lube and despite having metal 12” MC tyre levers (which I don’t like using cos they mark the rim unless protected) I used common, short plastic bicycle levers and some good old effort. It all went fine.

After a little centring at zero/very low psi using the moulded line on the sidewall and inflating to 30psi the wheel was back in and job done.

Installed width is bang-on, at just over 83mm. This gives a few mm clearance either side and is a little wider than the CST. The profile looks perfect, a nice rounded curve that isn’t flattened off due to being stretched, or too pulled in at the sides like when using an 80 width on an MSX sized rim.

After all that, I won’t be able to give a ride review for a week or so but it’s certainly looking ‘right’, unlike the CST. The K66 isn’t much heavier either at 2.2kg Vs 2.06Kg. Of course the K66 is also going to be far more puncture resistant being a proper tubeless MC tyre from Germany. It’s also load rated to 170kg. I’m not sure if this is the ‘SnowTex’ version or not, it wasn’t sold as such but neither does it have the white line going around the tread that I have heard denotes the non-SnowTex. So I don’t know but neither am I bothered tbh. I don’t do enough miles to worry about it.

A few pics. I roughed out a drawing of both tyres using a tile profile gauge. It’s not very accurate and I didn’t get the curvature of the K66 perfect but it gives you an idea:



Installed width:



Front view:



Wheel internal rim width:



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  • 2 weeks later...

Well after the massively high expectations of the K66 and doing my first 70 mile ride on it the other day..... I don't like it :crying:

It tramlines like crazy, I tried pressures from 20 to 40psi and it didn't make much difference although I would say lower was better. I can't convey how disappointed I am given it looks so right re the actual fitment for the width of rim and the resultant overall tyre profile. All my years of MC tyre experience was telling me this should work well but clearly EUC's are a totally different animal when it comes to what 'should' work. I honestly have no idea why it doesn't.

I could barely keep the wheel from jumping around all over the road, following all the small ruts and cracks. It was also a bugger to lean over at any speed and reminded me a lot of the Z10. It was even worse than the stock CST 186 and that was bad enough IMO.

So I have swopped out the K66 for a new Kenda 262 to see how that does. My head tells me it is so similar to the CST that it won't be much different but I have heard from a couple of guys that it rides much better. Will update further once I have given it a proper ride.

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1 hour ago, Planemo said:

It tramlines like crazy...following all the small ruts and cracks.

It's very unpleasant when it does that, a friend of mine had a tire that behaved like that and when I tried out his wheel I thought several times that I'd stall losing grip like on an oil stain or wet leaf, in fact it was just following tiny little ruts

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Well...I got my first ride with the EX on the Kenda K262 today...I honestly can't convey the night and day difference between it and the stock CST and the awful K66.

I planned to do a 30 minute test ride and noticed that straight off the bat all was perfect. I tested low speed handling, walking speed (inc U turn handling), high speed (only to 40mph though) handling, I also deliberately aimed for cracks/ridges/ruts in the road, potholes, road cambers and every other nasty road surface that I went out of my way to avoid previously. I also tested the carving at all speeds. The Kenda just behaved impeccably. It was just like my old Sherman.

I have no idea why the Kenda should be so perfect against the incredibly visibly similar but totally different CST186. I also cannot explain why the apparantly perfect profile of the K66 did so badly. It all totally goes against my years of MC experience. Clearly, EUC's are nothing like anything else when it comes to handling and for sure I will never make any assumptions about what should work again.

I can't express how happy I am with the EX now and its finally everything I expected it to be. I have gone from dreading the next ride, being pulled around like a bucking bronco to just riding a neutral handling wheel that goes and stays where I want it to. My confidence in the wheel has risen by 110% and I am back to throwing it around underneath me like my old Sherman within a 10 mile ride.

Why the archaic, blocky-treaded and very old-skool trials styled Kenda should work so well I genuinely have no idea. But it does. I will be ordering two spares asap :D

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  • 2 weeks later...
On 9/18/2023 at 10:56 PM, Planemo said:

 the awful K66.


For me is K66 excelent nimble tire on sherman clasic maybee rim diamaeter is te diference point. K66 exist like all year and like snow version what type you have?

I have all season version.

My sherman come with kenda 262 and switch to K66 day and night but positive. 

I not ride over 43km/h on sherman then i cant compare how feel in high speed both 262/k66.

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@Planemo it's good you found a solution you like so this post is more or less for anyone else who is researching tire shopping.

In my experience as well as the posts I took advice from prior to mounting a K66 tire, there is a required break in period with this tire. IIRC it took a few rides and I definitely did not like how it rode at first. There was a bit of instability and it noticeably accelerated slower being twice the rotating mass furthest away from the rotation axis vs my light cheapo stock tire. I also started with too much tire pressure too finding that 25/26 psi eventually worked for me.

If I were to theorize the reason for the why instability or tramlining behavior happens prior to break-in, it's probably because the tire contact patch that actually touches the ground meets at 2 opposing ridges and until they are somewhat worn down to create a consistent rolling contact patch, it's easy for the wheel to veer off-course in either direction. Once the tire wears in a bit, this tendency goes away.

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