CX Tires / MTB Tires / Rims / Tubeless Tire Tech

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27.5 + MTB Tires

Fat Bike Tires

Common Tubeless Tire Question:

How do I know how much sealant is in my Tire?


How Much Sealant do I have in there? 

It is impossible to know how much sealant you have in your tire without opening the tire.  But there is something you can do. Read below...

Avoid separating the tire from the rim if you can.  Let a tire stay seated and sealed unless you have to fix a puncture.  This is one of those situations where if you touch it, you may wreck it.   If you do take a tire off the rim, chances are you will need to  re-wrap the rim tape. If you don't re-wrap the rim tape, you will reassemble the tire add sealant, then figure out you have a rim tape  leak. Now you just made a wet sticky mess of replacing the rim tape. Sealant just got trashed too.

Always replace the Rim Tape when you completely unseat a Tubeless Tire.

How to tell if your Sealant inside a Tire is dry.

If a tire is dry, just add 2 - 3oz of new sealant and you are ready to roll. This works and it is my easiest method to check my tires.  I have 7 bikes with tubeless and never keep track on when I put sealant in. If I have not ridden one in a while, I always perform this 

Quick Check on the Sealant.

  • Align the air valve stem to the bottom of your tire, closest to the ground.
  • Release the air pressure.
  • Remove the center of the valve stem.
  • Let any fluid that maybe in the tire settle to the bottom for a minute or two.
  • Try to hold the tire up so it has a rounded bottom profile, not sitting flat on the ground.
  • Insert a long tooth pick down into the valve stem. 
  • Pull it out and check if it is wet or dry.  
  • If it is DRY, add another 2 or 3 ounces
  • If it is wet, there is no way to tell how much you have. 
  • Add some more if you like, up to you.

Video: Tubeless Tire Liners

I will be installing these soon... Looks like a solid product.

Hidden Performance found in the Rim Width

TCS Tubeless / Tubeless Compatible System WTB i23 29" Rim

What is Rim Width?

Rim width is a direct mechanical measurement of the inside of the wheel rim. A tire must be off the rim to make this measurement. Rim width affects how much tire is in contact with the road or trail surface.  All bicycles benefit from having a proper size rim width. Tubeless is another benefit to performance. It reduces the rotational weight of the wheel assembly, often up to 1 pound for each wheel.

Why is Rim Width Important? 

A tire will achieve more surface contact and the tire surface becomes more square to the ground as Rim Width increases. Good for Trails, Bad for Roads.  

Road tires want as little contact with the road as possible.  A narrow rim helps reduce weight and it keeps the tire round to have just the center of the tire in contact with the ground. 

NOTE: The Road-Tire contact pattern thoughts are currently in dispute. See the attached link to the video below:  Road Tire Pattern 

MTB's like as much width as possible. A 27mm wide rim can increase the amount of tire contact with the trail. Want more traction, go wider. Want a faster trail tire, keep a rounder tire with a narrower 23mm rim. 

Your ride can be greatly affected by Rim Width.  A wide MTB tire (2.3 inches) on a narrow 19mm rim is an unstable tire combination. It will have bad cornering, over steering, and a loss of traction. Some MTB's have 21mm to 23mm rim width, which is still too narrow.  A 2.3 inch tire should have between 25mm and 30mm inside Rim Width for best tire performance.

Important Note: You can go too wide on a rim size. What will happen is the tire bead will not seat correctly, and the tire will pop off the rim, which is a very bad situation. 

Look for Max Rim Width information on some tires.

Road Bike Rim Width

Road Bikes have tires that range from 23mm to 32mm wide. Max Rim Width for a road bike is 19mm. A rounded tire profile is preferred. Road bikes want as little tire/road contact as possible to reduce road resistance.

CX Bike Rim Width

CX Bikes have tire sizes from 30mm to 42mm. Most CX bikes have braking + traction issues on dirt trails, so you want the tire to sit as square as possible on the trail.  MAX Rim Width is 23mm for CX tires 30mm to 35mm. If you are running 35mm to 42mm tires you can go up to 27mm inside width.

Mountain Bike Rim Width

Mountain Bike tire sizes run from 1.9" to 2.5".  Mountain bikes have greatly improved steering, braking, and handling performance with wider rims.  Proper rim width for these tires is 25mm to 29mm.

Plus-Bike Rim Width

At the moment, 27.5 / Plus Bikes seem to have just (2) Tire sizes. 2.8" and 3.0" wide.  I have both 45mm and 50mm wide rims with 3.0 tires.  Honestly 3.0 tires are so good for traction and handling, I can not tell the difference between the 45mm and 50mm rims.  So, I would say, save some weight and go with the 45mm rims.

Fat Bike Rim Width

Rims on Fat Bikes range from 63mm to 83mm . Tire sizes range from 4.0 inches to 5.0 inches. Once again, with the huge width of the tires on Fat Bikes, Fat Bikes will never have traction problems.  The Tires will always have Weight Problems. The Tires will always have surface contact resistance problems. But some folks Love-Them... so that is what really matters.

Do I need a TUBELESS wheelset?

Who knew Tires could be so complicated!

Tire Selection and Tubeless Wheelsets:
Tires are the most important part of your bike. Tires win races and tires lose races.  You can squabble over what makes a bike better...hard-tail vs suspension, or gearing and geometry for what makes a bike that you like. It is important to know all the bike industries roll-out of shiny new objects are swamped out by your Tire Selection. Your tires make your bike better, or they can make your bike worse. 

Bike Manufacturers: Most tires supplied by the bike manufacturer are not the best tire for YOUR BIKE.  Unless you get a custom bike, or from a local bike builder, you will get a middle of the line Bike model that is built for the masses.  Trouble is, the trails here in New England are not like trails anywhere else in the country.  You will get a bike with tires meant for out West, or for terrain that does not exist here.  If you are buying a new bike, seriously look into upgraded tire options. Talk to the folks that know what tires you need, and get them installed. Otherwise you may not be totally happy with you new $3000.00 bike. Or keeping medium level tires on your bike, you are not realizing the full potential of your new super bike.

Tubeless: is one of the best options for your bike.  Many of the newly sold MTB's are running tubeless tires.  If you do choose to go tubeless, you must use tubeless specific rims with tubeless tires. You can get non-tubeless specific rims to seal, and hold air, but that will not last forever. A tubeless rim has a special hook design that matches the new tire designs to keep the tire from burping or worse... A tire could come off the rim completely. On a fast downhill, that is big trouble.

Since the introduction of tubeless, Pinch Flats have almost been illuminated.  (AKA: Snake-Bites because of the double holes they leave in the tube)  Pinch flats often come from low tire pressure and overly aggressive trail riding.  After thorns, pinch flats were the second most common type of tube flat.

CX / Gravel Bikes: Tubeless is a huge benefit for CX bikes. Still, not many folks use them.  With the very thin CX tire castings, tread patterns, and super lite weight, these tires are very prone to thorns and snake-bites equally.  Your CX bike would really benefit from a Tubeless conversion.  Almost 2 pounds of weight loss shedding the tubes, and you can run lower tire pressure for a softer ride and better traction.    CX tires gain a lot of traction in the 30 - 40 pound inflation range.

Note: On my long 40+ mile CX rides with tube tires, almost 1 tube change per ride. Since going CX tubeless stopping for tire issues is almost eliminated. 

Not everything is perfect: One main downside of tubeless tires is Sidewall Slicing. Sidewalls on mountain bikes are soft and flexible. This is a design feature for better traction.  As trail riding dynamics apply force to the tire during a bounce or jump, the tire will bulge under compression.  As this happens the sidewalls of the tires expand outwards beyond the width of the tire tread.  If a rock surface or other object is properly placed, it could slice through your tire's sidewall.  CX tire sidewalls slice just as nice.

Experienced tubeless riders know this happens more than once.  These incidents take a great tire and makes it junk in seconds, while ending your ride. Sidewall slices can not be repaired.  For this reason, always carry a spare tube with any tubeless wheelset. It is messy putting a tube in, but it will get you going again.

This was not an issue on Tubed Tires. With a tube in the tire, the sidewall is not nearly as flexible, and tire pressures run higher to avoid pinch flats. Also when tube tires were popular, the tire manufactures did not put a lot of focus on the weight of their tires. So a lot of tires had thick sidewall castings. Slight sidewall tears were also compensated for with the tube.  You would never know a slice occurred unless it was severe enough to penetrate the tube, which was a very rare occurrence... if ever. Many tire manufactures are all working on these sidewall issues, all trying to make sidewalls better as tubeless tires mature.

Sealant: Tubeless tires are also self sealing for small puncture holes. Could be from thorns or glass or sharp rocks.  About 3 oz of fluid sealant is resting inside the tire waiting for any exposure to fresh air.  As the puncture lets air out of the tire, a small amount of sealant fills the hole and quickly seals it.  This is great for MTB's that run low tire pressure.  On CX tires, you are running between 40 and 60 pounds of pressure.  Sealant has a much harder time keeping the hole sealed at these pressures. It gets pushed out, even after it has sealed for an hour.  

Tubeless Repair Kit: Recently a few manufactures have come up with a way to plug your tire while on the trails.  These plugs simply push into the tire, and when you pull the tool out, a rubber plug remains in the tire's hole. Then simply cut away the extra plug sticking out to make it flush with the rest of the tire, and you are good to go with a permanent tire repair.  (See below for these tools)

Tire Castings:

Casting is the method a manufacture uses to form a tire.  Because of sidewall slicing, it is highly recommended you get Thicker Casting Tires for the Rear. Front tires do not get sidewall slices nearly as often as the rear.  Mostly because at faster speeds your riding weight is shifted back over the rear wheel.   Shifting your weight back also helps your steering control at faster speeds. Fast speeds and tire bulge on transients means more odds of sidewall rock contact. 

Most tubeless tire manufactures offer their tires in both thick and thin castings.  The Thinner Castings saves weight. You are only talking a few hundred grams, but rotational weight has a multiplier effect. So the weight difference can be noticed.  Thinner castings also have a bit more traction in off-angle turns.  The sidewall flex helps the tire conform to the trail.  These statements are not ghosts.  There is an immediate and noticeable difference in tire castings.  Thicker castings are more slice resistant. Stiffer riding, and the sidewalls are not as flexible. 

TPI means what??

Tire thickness is often described in the terms of  TPI.  Threads Per Inch. Example: 120 tpi (thin) and 60 tpi (thick) sizes. 

Fitting 60 strands of rubber in one inch means the strands need to be large and thick. Fitting 120 threads per inch means much smaller strands to fit 120 of them all together in 1 inch. TPI is a number just like a wire gauge size. A higher number means a smaller diameter. For a lighter tire, each strand of rubber that is pressed together to make a round tire, is thinner @ 120 tpi than a thicker strand @ 62 tpi.  Often just a single weave is found on thin casting tires.  The Thicker rear tires not only have thicker strands, they may also double weave the strands in 2 different directions to give the tire more sidewall strength. 

Advice:  Do not get caught up in the tire weight game.  Get the thicker tires in the rear. Most tubeless tires are $50 - $70.  Thickness does not change the price. You can go thinner in the front. Long distance rides will feel a bit easier and steering more responsive.  If you are doing Rock Gardens, Down Hilling, and other risky riding, then get thicker tires in the front too.

Tubeless Wheel Building Video

Basics of Wheel Building. For any folks that want to dip into building your own wheel. 


Front:  29" WTB KOM i29 Rim / WTB Breakout 2.3 /  SRAM 15x110 Hub / 4.0 pounds with 180mm rotor.

Rear:  29" WTB KOM i29 Rim / WTB Breakout 2.3 /  SRAM 12x142 Hub / 12-36 cassette

With no screw-ups, it takes about an hour to build a wheel. Screw-ups happen often. Forgot to show the cross-lacing.  Spokes are very flexible, you will need to gently weave and bend the last 16 spokes to get them in.

Why Go tubeless?

ROAD Tire - rim width / tire size video

You have been wrong about Road Tires all these years: This video supports the conclusions I came to with the WTB Exposure 34c CX Road Tire.  My CX bike is a lightning-bolt on the road with the 34c tires. (see the tires below) They also sell a 30c version, without all the extra traction stuff.

The point of this video is the 23 - 25 cm wide road tires are losing speed vs 28 - 32 cm tires. Mostly do to the road surface contact pattern. Seems the slightly wider tires have a better footprint for corners, acceleration and braking. 

A typical road tire contact pattern is inherent to traction issues on turns and a rough rumbling ride from the higher tire pressures.  Something I have discovered many years ago as a former long distance road cyclist.  On even the slightest wet roads, road bikers know not to turn too fast, or SLAM Time. Thin tires seem like an inherently unstable design. 


SUBZERO ORANGE Tubeless Sealant


This is the only stuff that really works. Stan's does not work anymore, they lost the recipe. This stuff works when it is cold, and this stuff will seal that new tire that refuses to seal. 

Whenever I mention sealant, it is always SUBZERO ORANGE.


About Sealant: Sealant is added to a tire to help seal the tire to the rim, and to seal any punctures the tire may incur.

Sealant is not maintenance free. Let a bike sit stationary for too long and the sealant will pool up at the bottom of the tire, and start to solidify. Tubeless tires must be rotated at least every 2-4 weeks. After an entire season of use, the sealant may be mostly cured, so an extra 2 oz is probably needed at the start of the next season.


How Much Sealant do I have? It is impossible to know how much sealant you have in your tire without opening the tire. Avoid separating the tire from the rim if you can. Let a tire stay seated and sealed unless you have to fix a puncture. This is one of those situations where if you touch it, you may wreck it.  If you do take a tire off the rim, chances are you will need to re-wrap the rim tape. If you don't re-wrap the rim tape, you will reassemble teh tire add sealant, then figure out you have a rim tape leak. Now you just made a wet sticky mess of replacing the rim tape.

Always replace the Rim Tape when you completely unseat a Tubeless Tire.

How to tell if your Sealant inside a Tire is dry.

  • Align the air valve stem to the bottom of your tire, closest to the ground.
  • Release the air pressure.
  • Remove the center of the valve stem.
  • Let any fluid that maybe in the tire settle to the bottom for a minute or two.
  • Try to hold the tire up so it has a rounded bottom profile, not sitting flat on the ground.
  • Insert a long tooth pick down into the valve stem. 
  • Pull it out and check if it is wet or dry.  
  • If it is dry, add another 2 ounces. 
  • If it is wet, there is no way to tell how much you have. 
  • Add some more if you like, up to you.

Sealant Injectors:: Do not leave this stuff in your sealant injector for too long or you will need to throw it away. Within a minute of filling your tire, you must purge the remaining fluid.  I suggest a small cup of water. Draw the clean water into the syring and squirt it out into the trash. Do this a few times till it is clear and clean.

ICE READY 27.5 Plus

Ice ready 27.5 Plus


Perfect Knob Spacing for studs.  I have seen some studded tires totally loaded up on too many studs. This pattern only uses 60 studs per tire. Though on tubeless rims, I went with tubes. If a stud pulls out, sealant may not be able to seal that hole.

Because of the rounded tire pattern, when these tires are pumped up to 40 pounds there is almost no stud contact with the ground. However just drop that pressure to 25 pounds, and the tire flattens out for full stud contact.

Thick Sidewalls and Big Knobs


Found these sweeties for $32 each.  62 TPI sidewall and Big Knobs to hold the Auger Studs.  Perfect Snow Tires. I picked the 2.8" size to keep the tire narrow for  better snow traction.  

After riding a Fattie for 5 years in the snow, I have learned that a wide tire is not always best.  Trying to stay on top of the snow takes a lot of work.  A thinner tire has the ability to cut through the top-fluff and find solid traction underneath. 

Tungsten Auger Studs


These studs were used for 2 Winters on 2 different tires.  These studs are reusable. This is the Third Installation.  These buggers are expensive at $1.00 each. But they are Tungsten so they should last forever.  I also put a few in my Riding Boots.  If you put your foot down on Ice, you will want the grip.


Stud Installation Depth


Shown is an  Auger Stud installed properly on a tire knob.  As with any studded tire, you can expect to lose studs on rides.  These studs really stay put. Only one time when I had to ride on the road for a bit did I lose a couple of studs.  You do not want to ride on pavement with studded tires... trust me... plan around that.

Tire Tech and TUBELESS Repairs


Tight Tire Installer

Tire / Rim Sizes: Some Tires and Rims are not made the same. Different standards and different Tire Bead (hook) designs. 

A few years ago a Tubeless Tire Standard was developed, but there are still many tires and rims that do not meet these standards. Tires will be Tight or nearly impossible to install on the Rim.

For these situations, you can use this Tire-Puller. (By Koolstop) A neat tool that will help you install your Tight Tire without Rim or Tire Damage.


Tubeless Trail-Side Puncture Repair:

For Higher Tire Pressures over 30 pounds, some of the other Tire-Plugs would push-out of the hole you just tried to seal. Dyna-Plug claims their metal-tipped plugs solve that issue.  

This tool has storage room for 10 Dyna-Plugs inside the Handle. I would guess you are having a really bad day if you ran out of plugs on one-ride.

Gorilla Tape installed: Shows signs of creasing and is surrounded by tire sealant.

Fixing that Slice in your Tubeless Tire

Black Gorilla Tape vs Standard Tire Patches. Both work fine, but maybe One is better? 

 I have found strips of Gorilla Tape to repair a Tire works very well. Even after many rides, I open the tire to check how well the patch is doing. 


SHOWN: (29er tire) The Tape will have some Creasing with tire sealant inside, but holds tight. (Stan's Sealant) 

A Standard Tire Patch, works good too, but have found they pull off  much easier than the tape. Have seen signs of seepage under the patches too. Standard Tire patches  will never hold up under tire flex.

I feel the Gorilla Tape is Best.  Keep you updated.

Tech Note: Always turn a Tubeless Tire Inside-Out when working on it...

Tubeless Repairs

Tubeless Tires should be Inspected often.


This knob has just been repaired. This knob has a slice at the base almost 1/3 of the way through the knob. It would have eventually torn off. This tire had 6 side knobs with slices in them.  This is a back tire with over 500 miles on it.  The tread has not worn very much even though these tires have been on very rugged trails.  Most tires never make it to the end of life because they are torn, or punctured before the tread wears out. Sidewall Slices and Torn Knobs will junk your tire.  It is very typical that tires and knobs sustain this type of damage. 

For Tubeless Tires this is a big issue.  If you tear a side knob off your tire, chances are the sealant will never seal that  hole, and you will be stuck on the trail.  Some folks carry a spare tube for such emergencies.  If not, you are bumming out.  Head off this issue by checking your tires every month.  This tire had 6 knobs that needed repair.  The rubber on the repaired knobs was separated, and the glue meld them back together.

This is not much of an issue with Tubed Tires.  You could lose a knob, or even catch a sidewall slice and the tube would hold the air.  You may have torn knobs and never know it.

Fixed Knobs


After the Cement Dries, the knob that had slices is now joined back together. When tires are more than $50 each, this is a great way to extend the life.

Best Tire Repair Tool


This is a Life Time Supply of Rubber Cement. 

This can maybe more than 10 years old.

 Found at your auto-parts store for about $5.00 a can. 

Read the instructions for proper use.

It must be dried before applying Patches.  

Tubeless Repair Update:

Gorilla Tape is the Clear Winner.


Turns out the Gorilla tape repair is way better than I could hope.   While the outside (Black) layer of the tape easily peeled off, the mesh network of glue and fibers (adhesive layer) made a tight bond with the tire surface.  The Sub-Zero Orange sealant was the catalyst that bonded it all together.   I removed the black outer layer, and tested the strength of this bond.  It will not be coming off.

Update: 9-2018: Have also recently successfully repaired at 4.8" Maxis Fattie-Tire with a large side-wall puncture.  Because of Side-Wall Flex, I did not think the patch would hold.  After 2 months of use on tough New England Trails, the Inside Gorilla Tape Patch is holding fine.

Full View of the Patch


The reason why this patch is so large, there were actually (2) different punctures in this same area. 

One large patch fixed both issues.  However, the reason why this tire is open, is for a 1/4 long sidewall rip. Do not feel I can repair this safely. So, this tire will be converted over to a Tube-Only tire. 

Sub-Zero Orange Sealant


There is a reason why I keep plugging the Sub-Zero Orange Sealant. The Stuff Works...!

As seen in this photo, the sealant has formed a tight membrane at the tire bead where it hooks into the rim. For some reason, the sealant needed to repair an issue that went unnoticed by the rider.  This will not come off of the tire without a lot of effort, and I still will not get it all off.

MTB Tire Construction Video


What is This?


You are looking at a 2.8" tire with a pressure rating of 17 - 38 pounds.

This photo was taken after 50 pounds of air-pressure was applied.



The Loudest Noise I have heard in a long time. 


Worse part was the Tire Sealant.  It vaporized and exploded out in a mist-cloud. The first time I blinked my eyes, I knew I was in trouble. 

Makes a good hair gel too.



62 TPI tires are very thick. 

This was one hell of an explosion.

 Be very careful.

VIDEO: Fat Tire Grip-Studs / Traction on Solid Ice

I have installed these on my Vee Missions, and they work exactly as this person's  Video explains.  See my mention of the Grip-Studs in the Fat-Tire section above.

You can expect to lose 1 or 2 studs each long ride. All brands of studded tires have this same issue.

Can Not Ride on Pavement, Period.  Same with most Studded Tires.

I also installed them on my Winter Boots for foot traction while Ice-Biking and Driveway Shoveling. 

CON: They are $0.99 each Stud, and you need 70 per tire.

VIDEO: Skinny Studded 29" vs Fat Bike 4.8 inch in Snow / Ice

Disclaimer: I have a BIAS against Fat-Bikes.. this video shows all the same issues i had while riding Fat Bikes.  I tried 4 different Fat Bike Tires and Wheelsets... Then I converted my Fattie to an E-Bike and now I love it.