Honda CG125 Front and Rear Tyres and Changing
Tyre Pressure
When is a
Tyre Worn out
How to mix Tyres
How to avoid falling
off the bike with new Tyres
Inner Tubes
Tyre Makes
and Models
How to find the best price for
Tyres
How to remove and
install the wheels in the Bike
Tyre Pressure
Front Disc Brake model, Front 25 psi, Solo Rear 29 psi,
Passenger Rear 33 psi.
Front Drum Brake model, Front 25 psi, Solo Rear 28 psi, Passenger Rear 32 psi
(40 psi for 1976 to 1984 models = 17 inch wheel).
Always test tyre pressure with a stone cold tyre (leave overnight to cool).
Stay away from garage air pumps (they can substantially over or under inflate
motorcycle tyres).
Large changes in outside temperature will change pressure in tyre.
Dependant on inner tube or valve, tyre will loose air dependant on ether length
of time or mileage (or speed and mileage).
When is a Tyre Worn out
A tyre (tire) will wear out, you will probably find the bike suddenly feels
like its riding on ice round corners and goes round like a lorry.
In old age, the tyre can suddenly lose its strength or collapse leaving the
inner tube to take the weight, this will also lead to very bad cornering.
The tyre manufacturers recommend you have 2 mm of tread left in order to grip a
wet road.
I have often found tyres are worn out at 2 mm or just below, the tyres feel like
you are riding on ice even in the dry.
But it will depend on the make and model (some designs of tyres may not show any
signs even with no tread left). In the UK the legal minimum tread depth is 1 mm.
How to mix Tyres
Its important that the front and rear tyres are designed to
work together,
mixing different makes and models is a bad idea unless the
manufacturer states they are designed to work together.
Its also a good idea to change both tyres at the same time
(unless the front lasts twice the mileage of a rear),
since the old tyre affects how the new tyre runs in,
also tyres go round bends differently when they are new
compared to worn (you want both the front and rear tyres to go round a bend the
same).
How to avoid
falling off the bike with new Tyres
When you have new tyres, there is a manufacturing residue left on them that needs to be worn off.
The amount of residue and slipperiness depends on the tyre,
the manufacturers advise you to run a new tyre in for 150 miles.
You must start off slowly, reduce your speed, acceleration,
braking and cornering.
Slowly increase your speed, acceleration, braking and
cornering during the 150 miles.
This running in time will also teach you how the new tyres
corner and perform,
your old tyres at the end, are totally different, even if
they are the same make and model,
since they are a different shape due to the unevenly worn
parts of the tyre.
A tyre that runs in a straight line most of the time, wears
more at that part than the cornering part.
Many people have dropped their bike on the first bend they come to on new
tyres since they forgot about running in the tyre.
Even experienced riders with large expensive bikes have made the same mistake,
do not make the same mistake and be very careful for the first few miles (I keep
speed below 40mph and do not lean the bike on any bend for the first 5 miles).
Inner Tubes
The inner tubes do not need to be replaced every time you
change the tyres, it depends on age,
if there is a problem the shop should tell you when they see
them (they will look for cracking, stretching and other ageing things).
I have been told by tyre fitters they have seen 10 to 20 year old inner tubes
that have been used and are still fine (that does not mean every inner tube is
at that age).
I would advise you to use Michelin inner tubes, since they are noted for their
quality and lack of air loss.
Tyre Makes and
Models
The original tyres would have been 2.75-18 Front and 90/90-18 Rear tyres
(1976 to 1984 models need 2.50 -18 Front 3.00-17 Rear).
The quality, performance and safety of the tyres you buy are critical to your
safety, enjoyment and for passing your test (if your in the UK).
As well as how many miles they manage and loads of other factors, so I strongly advise you read all
of my reviews on tyres (links to the reviews are in this section).
I highly recommend the Michelin Pilot Sporty tyres, see my review Michelin Pilot Sporty Tyres Review
The 90/90-18 rear is only available in the UK in (at the time this webpage
was last updated)
Michelin Pilot Sporty.
Pirelli City Demon (might not be available, check with the importer), see
my review Pirelli City Demon Tyres Review
Metzeler do make one but the UK importer refuses to stock or order them.
Sava (owned by Goodyear) but its not reinforced like the others so the maximum
weight (bike + rider) on the tyre is only rated at 195 kg compared with 230 kg.
2.75 - 18 front is available in the UK in several different makes and models.
3.00 - 18 rear is available in loads of different makes and models in the UK
but,
I advise against using a 3.00-18 rear tyre size, the bike's
original tyres are 90/90-18 rear for a reason,
the tyre firms will tell you
3.00-18 is imperial and 90/90-18 is the metric equivalent, but that's not true.
The 90/90-18 can carry much more weight (do not use a 3.00-18 with a passenger
unless you are both light), 230 kg (max bike + rider) compared to 200 kg.
The 90/90-18 is wider and lower than the
3.00-18, this effects the cornering abilities of the bike,
people who have tried
the 3.00-18 report the bike is unstable going round bends (twitchy).
If you
insist on having a 3.00-18 rear, a Continental ContiCity (seems to have been
replaced by ContiGo) tyre might be the best?
In the past it was not possible to get 90/90-18 rear in the UK, so some people
were so desperate to get a wider tyre than the 3.00-18 they fitted 3.25 or
3.50-18.
The 3.25 and 3.50 are wider than a 3.00 but they are also taller (taller tyres
will change the weight distribution of the bike so affect cornering).
I advise only to use a 90/90 tyre since it is the correct width and height,
90/90 is nearly as wide as 3.25, a tyre that is not wide enough or to wide will
affect cornering.
How
to find
the best price for Tyres
Shop around for the best price for the tyres, some car tyre
shops will supply and fit to loose wheels and some even to the bike,
they can sometimes (not always) be substantially cheaper than a
motorcycle shop.
Some motorcycle shops can even charge a fortune to fit to
loose wheels, so the message is simple, shop around.
Mail order is nearly always more expensive, since you need
to pay someone to fit the tyres to the wheels,
many shops (especially car shops) do not charge to fit new tyres to loose wheels
if they supply them.
It's often a lot cheaper for you to give the tyre shop the wheels loose, they often charge a fortune to remove and put the wheels on to the bike.
A tyre shop needs to know which way round the wheels move when the bikes going
forwards (some wheels have the brake on the right but others are on the left).
That's because motorcycle tyres are directional, make sure
they have got the direction correct, look at both side walls of the tyre,
on one side there should be a direction arrow pointing in the direction
the tyre will move when the bikes moving forwards.
If the tyre is universal fitment, it can have 2 arrows,
on one side of the tyre it will have an arrow and say front
and on the other side an arrow pointing in the opposite direction and say rear.
If the tyre is being fitted to the front wheel you need the
arrow that has front next to it, if it's a rear wheel you need the arrow that has
rear next to it.
How to remove and
install the wheels in the Bike
The Owner's Manual (you can manage without it) tells you
everything except.
I found I did not have to loosen the rear wheel chain adjuster nuts,
I
simply removed the rear wheel axle nut and slid the whole adjuster off the
spindle and bike,
this meant I did not have to check the wheel alignment
afterwards.
Both wheels have metal spacers on the wheels, some are
partly
inside the wheels, make sure you do not lose them.
It only takes one person to remove the wheels, I strongly
advise it needs 2 people to put them back in again.
If you do not have the Owner's Manual, below are the
basics.
Rear Wheel
Remove the rear brake adjuster nut (1) at the wheel end,
remove
the brake rod (2) from the brake.
There's a rear brake arm (2) that stops the
brake spinning with the wheel,
remove the small pin (3, you will probably damage
it so buy a new one)
that stops the nut (4) from being removed at the brake end.
The small pin is called a Cotter pin, its basically a piece
of metal folded in half,
it goes through a hole near the end of the screw
thread.
The 2 pieces that have gone though the hole are then
separated
and folded up and around in opposite directions around the nut.
Remove the nut and pull the arm off the brake.
If you have a fully enclosed chain, you will have to remove the chain guard, see
Enclosed Chain Guard
Remove the rear wheel axle nut (might have a small pin to
stop the nut being removed like the brake) on the right hand side of the bike.
The nut is normal type, anti clock wise to slacken, clockwise to tighten,
if your not strong enough to slacken it, tap / hit the spanner with a hammer
several times quickly, if
that fails get a longer spanner (to get more leverage).
Remove the right hand side chain adjuster
(diagram shows the left hand side, the right hand side is identical).
Put your foot under the wheel and remove the rear wheel
axle and then remove the chain.
To reinstall the rear wheel, reverse the process, to setup
the rear brake see Rear Brake in
Brakes page.
Front Wheel
On the left hand side of the wheel there is a speedometer
device
and a cable connecting it to the instrument panel,
remove the cable at
the wheel end (there's probably a screw to remove).
If you have a front drum brake, remove the brake cable.
Remove the front wheel axle nut (might have a small pin to
stop the nut being removed like the rear brake) and slide the axle out (wheel
will then fall out).
The nut is normal type, anti clock wise to slacken, clockwise to tighten,
if your not strong enough to slacken it, tap / hit the spanner with a hammer
several times quickly, if
that fails get a longer spanner (to get more leverage).
If you have a front disc brake, do not touch the front
brake lever while the wheel is out of the bike.
When putting the front wheel back in,
look at the
speedometer device and the left front fork,
they need to line up with each other.
The speedometer device has 2 metal pieces sticking out,
the
left front fork has a single piece of metal sticking out,
put the fork metal sticking out in between the 2 metal
pieces of the speedometer device.
If you have a front disc brake, you will need to use the
brake lever a few times before the brake works.
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