There is alot of fear or confusion  about tubeless tyres but in reality they are the easiest tyres to live with.  As not all tyres are created equal, tubeless tyre choice is important but the majority of tubeless issues, are user error - simple as that. Below is a guide to avoid user error. I have worked this all out by trail and error (alot of error on my part as well). 

Tubeless tyres work best at lower pressures than tubed tyres. If you insist on 90 psi then your asking for punctures that don't seal and plugs that blow out. You are also not quicker, on smooth roads maybe but its marginal but unless your doing a time trail it really does matter anyway. 60 psi works well for this 90kg rider with load too. Punctures seal more quickly at lower pressures and you can plug a bigger hole. Also 90 psi kind of removes the advantage of tubeless tyres which is lower pressures which is maximising comfort and grip.

First of tubeless tyres should be run with sealant. Some insist on riding without sealant. Riding without sealant can be done on proper UST rims and with a few tubeless tyres, but I would not do it, too much flint in Suffolk to take that risk. There are many brands of sealant, Orange Seal, Stan's no tubes, Effetto mariposo, Zefal, DT Swiss, Schwable even IRC do one. they all work in similar way. The latex is in solution and mixed in are particulates so when you puncture the sealant is forced into the hole and and the particulates fill the hole that the latex sticks to causing a plug to form. Using CO2 on your tubeless tyre with sealant in can cause problems though but it can also be useful to carry too.

Stans for example will turn in a white watery liquid when CO2 is used which is about as useful as chocolate teapot, in fact less useful, I can eat a chocolate teapot. If you use CO2 to inflate tyre just mounted add more sealant through the valve core, the tyre should remain locked to the rim so you can then inflate with a track pump.

Most brands of sealant I have tried do not mix well with CO2. Sealants with a high gycol content (you can smell it) are not affected by CO2 much. MaXalami MaXSeal is an example of such a sealant. 

CO2 is particularly useful if your tyre unseat with no pressure in them or unseat with little force. In this case a hand pump is not going to help you. A shot of CO2 will however get the tyre seated and inflated again. 

Sealant dries out slowly. It needs to be topped up. I top up my IRC tyres every 3 months or so, or when I feel it needs it. If I am being honest I normally find out I need to add sealant if I get a puncture that seals only at low pressure. That is the sign I have left it too long. 50ml in a road tyre  is sufficent. I inject sealant through the valve core using an injector . I dont bother checking how much sealant is in the tyre normally I just pour some in because I normally leave it long enough there is little in the tyre. If you want to check then use a thin zip tie as a dip stick. 

You cant over fill the tyre dont worry about that and there is no need to clean old sealant out. This is true if you sealants that don't ball up.

If you keep the sealant topped up you will find it will seal most punctures (if not all) pretty quickly. You can get a fair bit of air loss but even if you drop to 30 psi you can still ride on that. So you can stop and faff with a small pump or continue riding and use a track pump at home. I have done the latter as I dont often have a pump with me I come to that later. This is the problem with 23mm tubeless tyres. The air volume is small and therefore the pressure drop is large before the tyre seals. Bigger tyres can seal at a higher pressure due to the larger air volume. This make larger tubeless tyres more practical. I consider 25mm the minimum size for a tubeless tyre for this reason alone. 

Sometimes however the sealant just cant seal the hole. Most of the time that is because there is insufficient sealant in the tyre but sometimes it is because the hole is too big. At this point many people get out that spare tube and faff trying to get the tyre off, fit a tube while getting sealant every. Then swear alot and ruin their thumbs trying to get the tyre back on again. No wonder some give up on tubeless tyres after that. There is a solution though. In my back pocket is Loctite flexible superglue and normally Maxalami tyre worms (there are other brands too). The worms are fibrous strings with tacky butyl rubber that come with an applicator. Before the tyre goes flat you place the worm with the middle in the applicator and shove it into the hole.

The Maxalami kits offer two sizes of worms for different size holes. 1.5mmx5cm worms and 3.5mmx10cm worms. I carry both always. Carry just the small ones and the hole you get maybe too big for one small worm. So it cant hold pressure and blows out. Put the bigger one in and you'll be fine. Make sure the worm is properly inserted and watch the video showing you how. This will plug the hole and the excess worm does not have to be trimmed. The excess will flatten off and disappear into the road with in a few km. Sometimes a worm by itself is not always enough to seal at high pressures (this has been the case when using small worms in big holes). If this is the case get the flexible superglue out. Smear that over the worm and hole. Let it set then inflate. I would be wary about inflating to very high pressure straight away. I would put enough air in to get me home and no more. When you get home you will want to trim the worm if the excess has not gone gone already (or carry nail sicsors) with you.and you can then make sure there is enough glue covering the hole before trying higher pressures. Remember a 25mm tubeless tyre is run at not more than 85 psi anyway.

Worms can be a permanent fix. I have ridden for 1000's of km on tyres fixed with them. Likewise I have done 1000's km on tyres fixed with flexible superglue alone. 

Sidewall cuts can be dealt with using the flexible superglue or worms. I would try the flexible superglue first on small cuts/holes. you may not be able to hold high pressures but you can get the tyre to hold enough air to get you home. This again is permenant fix I have used this trick one than once. The alternative for bigger sidewall holes is a worm. If the appropriate size and shove it in. A plugged tyre even in the sidewall will be safe to ride in the long run so long as it not bulging. Bulging tyres are compromised and should be retired. If your tyre is bulging after repair and you still have to ride home inflate to a bare minimum pressure 30 to 40 psi and take it easy - this however is not advisable. Bulging tyres should really be ridden at all. 

Tubeless tyres can be repaired if they have a butyl or latex lining. IRC's tyres do, many other do not though. If you have a proper lining then you use a inner tube patch and vulcanising rubber glue to seal the inside of the tyre. For tyres without a lining you may need your superglue again to get the patch to stick. You can do this if your plug/superglue fix starts leaking air. There are tubeless patches too. these are often too big for road tyres but are thicker and will reinforce the tyre casing. The tyre has to be removed though so see if the external fix works first.

Be aware though that the bead on tubeless tyres stretch so removal may lead to them not reseating. In general leave a tubeless tyre in.place until it time to be replaced. I never attempt a patch on mine as by the time they benefit from a patch they are worn out and half dead anyway. 

So what you dont do is fit a tube to fix a puncture issue with tubeless tyres. If you carry a tube ask your self why, the hint is in the name TUBELESS!!!!! If you note the issue above your going to have faff later. 

What I carry;

When I am commuting on the commuter bike with two big panniers I have tyre worms, flexible superglue, a pump, CO2 sometimes (depending on the tyre/rim I am using), valve core remover and a 2oz bottle of sealant.

 

When riding my race bikes I just carry flexible superglue, worms and a pump/CO2 and that's for 200+ mile rides as well. For long TT's I carry nothing mainly because my skin suit has no pockets.

The thing is even if I carry what I do on the commuter bike it still takes up less space than tubes and levers. I do not carry a tube or tyre levers. As far as I am concerned my tubeless tyres once fitted will remain on the wheel until they are worn out, unless I have to patch it which thankfully I have had to do only once. 

So I hope that helps answer questions about riding with tubeless tyres. I have given up on clinchers with tubes and won't be switching back.