206 Slower on New Tires?

Currently running OTK STV chassis in 206 and I have an issue that as soon as I put sticker tires on my kart locks down and would slow down .6-.7 sec/lap on a 33 sec lap. The point in is great with new tires but it’s just slow.

So far i’ve got a shortened HH axle
MXC wheels
Beasley cik seat (6’ 1" @ 200lbs)
way lower tire pressure

Any additional thoughts to try?

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Where is it slowing? Data will tell you, compare old and new tyre best session laps

Sounds like it might be getting “stuck”, “bound up” or feels “bogged down” like the kart is down on power out of turns?

If that’s the case, I’d probably go up on tire pressure. But there are other things you can try to unload the inside rear tire (or keep it unloaded for longer).

Hopefully someone can give you OTK specific advise, but in the absence of that, here’s some things to try.

You can add caster (Although this helps more on entry vs exit), narrow the rear track width, or add a seat stay on each side if you’re only using one.

Camber can also help control how the inside rear wheel unloads as you exit the turn.

It sounds like you may have set your kart up really well to perform on scrubbed/used tyres.

Add some caster, seat stays and bring rear track in. See how it feels on new tyres and go from there.

Just be wary of inducing too much grip/lift into the kart. Sometimes when the kart is flat and bogging on new tires, it’s because the added grip of the new tires is causing the kart to lift too harshly and it sets the inside rear tire down too quickly. On a kart with more power, this typically manifests as a hopping conditions, but in a 206 it may never generate the forces necessary to hop, and it might just sit flat.

If none of the above suggestions work, you may have to go the other way on your adjustments.

Your axle choice seems correct, as well as going to MXC wheels and dropping pressures. If the handling issue is happening right out of the gate on new rubber, it’s likely not going to be fixed with tire pressures or wheel choices, it’s a fundamental balance issue with the kart that needs to be adjusted.

If the above adjustments fail to improve it, try going with negative camber and widening the rear. The negative will help the kart roll better through the center of the corner and will reduce some of the initial harshness (if that’s the issue) on turn-in.

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Different kart, same problem. Need clapped out old rubber on mine. :man_shrugging:t2: Track is a weird animal.

Add width to front, add caster, narrow rear, increase tire pressure by 10psi or more, seat struts, change Ackerman. Just start seeing what works and what doesn’t pretty much how I do stuff keep trying new things and if alittle is good, then add alot till its not good anymore then back it off till you find the maximum from that adjustment. . Lol

I watch my own bobber for sure, call my kart the Wonky Donkey

Not to highjack the thread, but maybe going to a softer axle might help lift that inside rear so it doesn’t side and get stuck… I know the manuals and OTK products say go stiffer when there’s a lot of grip. But… soft creates flex which should help generate lift.

I may be wrong but please Correct me @tjkoyen

Thanks for all the replies everyone, I got around to pulling the data and thought i’d show it for the good of the forum.

I’ve broken down the lap in 7 sectors to show that the new tires really are slower everywhere on the track. Green is the fastest on new tires, purple is fastest on old tires. Total time between runs maximum of 5 mins.

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I havent gotten a chance to get back on track, I will likely be starting with increasing the negative camber. I can not go any narrower on the rear without cutting more off my 960mm axle. This weekend is rain so it will be a little longer yet until i can test some more.

Don’t test more than one variable at a time.

To lift the rear wheel more, you need a stiffer axle not softer. Softer allows the outside rear to sit flatter to the track thus lifting the inside rear less

Use a stiff axle in low grip conditions to give the outside tyre more bite (smaller contact patch therefore higher psi of downforce pushing it into the track), high grip well rubbered track you can go softer for a higher contact patch to make use of the rubber on the track and less lift to allow for earlier traction out of the corner as both tyres make full contact sooner

Experimenting with axles is a good area to explore, they make significant differences to handling.

Just be aware that some karts behave as Richard noted and others behave the opposite. Almost all my experience is with TonyKart or TK style chassis and I’ve always gone “softer” in low grip conditions and “harder” in high grip conditions. I would test both. Also, be aware, that testing on non-race weekends may not provide the correct information. You might need to sacrifice 2-3 race sessions to determine the right direction because the track may need to be rubbered up.

As mentioned before. Its not only on otk brand. When the track is rubberized on a soft axle there wouldnt be enough lift and the inner tyre would stick to the ground, so therefore you wozld also have to go for a harder axle. Another example. With a stiff axle and low grip condition, you would put to much side bite on the outer tire. Especially on a harder compound the tire would overload since due to low grip condition and more jack only the outside part of the tire would get the load. It means less contact and more forces on a smaller surface (otter part of the tire) and the kart would start to slide. A right axle stiffness is a real science. So in general this is hard to say. It depends how you chassis us working in certain conditions.