Next I am going to go over some of the things you should consider buying or having on hand when you decide to change your tires.
Tires – First you will want a fresh tire or pair of tires that are going to match your wheels, your terrain, and your riding type. Our favorite for in the north west is the dunlop MX 51 , the dunlop mx51 is a good intermediate tire:
Lets start with tire sizing, because the focus of this site is Motocross, and mainly Big Bike class dirt bikes I will only cover common sizes used on those bikes, and only give you information on current sizing practices or types, and we will get into vintage, minis, and sizes or conversions for them in another post some time.
So lets consider a 450 class bike, at a glance you would think that 250/450 are about the same, not completely true…the 450 commonly runs a wider rear tire than the 250 in most cases.
-So for the 450 class bike rear wheel a 19 x 2.60 (Diameter and width), your most common used rear tire size is: 110/90-19 (Width / Height – Wheel Diam).
You can also run several other sizes like: 120/80-19 , 120/90-19 , 110/80-19 , 100/90-19 , 100/80-19 to name a few. With the 120* sizes you are getting a wider tire, and with the 100* you are getting a more narrow tire.
Then you have the height of the tire, you can think of this as the distance from the rim to the ground when considering tire height. Honestly, to the occasional rider, and the untrained eye, most would not notice the difference between the sizes. The main thing is to get the tire that meets your manufacturer specified sizes for your bike, fits your terrain, and riding style.
As for the front tire on a 450cc class bike and a 250cc class bike you are most commonly going to find a:
– 80/100-21 tire for the 21 x 1.60 wheel that is commonly used on both bike sizes. You may also find sizes like 100/100-21, 80/90-21 , 90/100-21 and so on available, but we prefer to stick with the 80/100-21 tire size.
– The rear on a 250 class bike is generally a smaller width rear wheel 19×1.85 but the diameter is the same. with the 250cc class bikes you will find it more common that they run a 100/90-19 tire, this helps the engine to not strain as hard turning a larger tire and wheel. That’s not to say that you cant run something like a 120/80-19, yes it will mount but its not recommended. It’s also not uncommon for a rider to mount the 110/90-19 on the 19×1.85 rear wheel, we haven’t seen any negative performance differences with this tire on a 250 class bike.
** Some of these size bikes you may find equipped with an 18in rear wheel, this is more common with the X and enduro type machines and we will cover more on that in another article down the trail.
Some of the things people forget to consider when changing a tire are:
– Rim locks, these are the rubber “foot” that has a threaded stud in them that pulls the bead of the tire to the wheel keeping the tire from turning on the rim while under load. a Rim-lock is important, and should be replaced when they start to crack or deteriorate. A rim lock is a relatively cheap item and should not be over looked when you change tires.
Rim locks are sized to match the width of your rim. For instance they are available in 1.60 , 1.85 , 2.60 and so on.
The rim locks match the wheel or rim width so a:
–450cc class bike will run a Front 1.60 / 1.40 and Rear 2.60 / 2.15 rim lock combo.
–250cc class bikes will use a Front 1.60/140 and Rear 1.85 rim lock set.
The 250cc bikes and 450cc bike run the same front rim lock as many bikes and is generally a 1.40-1.60 universal size Rim Lock for front rims. The rear rimlock size is different between the two bike classes. The rear rim locks are sized to match the rim width of the motorcycle.
No one really sells them as a kit or pair but I have matched them together for you from amazon, there are generally 2 price ranges for these, the Motion pro a more of a hard plastic Rim lock, they tend to last a long time, but are more expensive.
Then there is the the alloy or steel rim locks that are rubber, similar to OEM rim-locks from the manufacturer:
I have run into the problem at the track where they only had the larger of sizes (Rear rim lock), and I needed a 1.60 in a pinch. You can gauge the size of the rim lock when set into a wheel that does not have a tire installed and cut off the wings on the sides of the rim lock to make it work for that race or ride with a pocket knife or razor, as long as you don’t expose any of the metal when cutting them down.
Another item to consider is a set of:
–Rim lock nuts, they are normally a nut kit that includes both the rim lock tower or castle nuts for both wheels, the tapered spacer or washer that sits flush with the contour of the rim, some kits may also include valve stem caps, as well as a spacer, washer, and nut for the tube.
These come in all sorts of anodized colors to match your ride. **Take care not to cinch these down too tight as they are mostly all a light aluminum and will strip out.
The next thing is the you need to think about is:
– Rim strips. often over looked, a rim strip is very important… this keeps a protective barrier between the spoke nipples, and the tube. This prevents damage from pinching, puncturing, chafing, and also protects from some small dirt that make it past the spoke nipple. These are cheap, and honestly they don’t last long, its a good idea to replace these every few times you change a tire and inspect them every time.
Motion pro makes a rimstrip tape:
There are a variety of rimstrips available in the normal rubber type:
Also in a bind you can use black tape, duct tape or what ever to get you by but it wont last as long and should only be used as a temporary fix for the sake of your tube!
And at last you need a:
-Tube, there is a giant selection of brands available, generic, name brand, heavy duty, ultra heavy duty. What is important to me is cost, i want a cheap tube that is slightly heavier than your generic tube, Like the IRC tubes, great price thick tube:
We have used about every brand out there, bikemaster, cheng shin, irc, bridgestone, a tube is a tube no need to spend big money on a name brand, they are all about the same other than some are heavy some are not. Its always a good idea to buy them in pairs for each wheel so that you always have a spare on hand.
When it comes to cost, some times its a better idea to think about having fresh equipment so that every time the gate drops, you can focus on the race, not the bike.