tire size question

[alph]

my yamaha cycle calls for a 110/90 18 tire for the back, and a 90/90 18 for the front.  i found a set of Dunlops i like, but the only size 18" they have is 120/90 rear, and 100/90 for the back.  i have enough space between the forks and swingarm to accomidate the different sizes, but is it "safe" since i intend this bike for my daughter.

thanks.

[N8171S]

If you have the room it is probably safe.  I tried to go up one size on my BMW R1200C and they wouldn't fit.  Running a 205 60 16 on one of my valks for over 35,000 miles without any problems.  Might throw the speedo off a little.

[valky1500]

Tire clearance is only a small part to consider when switching to a car tire on a motorcycle rim.

The biggest and most important safety issue when going darkside is the valve stem clearance and placement which is of utmost importance. Also, they are not all made equal. Using a motorcycle valve stem is the only way to go as the Centrifugal force will pop them out of the wheel when spinning fast.

Another thing to realize is that valve stems on motorcycle wheels are in the middle instead of on the edge like with cars. So they must either be short and straight or short and angled to be able to get air in them. Either way they must be screwed on and seated tightly. If you don't want to change anything then use the same piece that comes with the Valkyrie to hold the valve stem in place or they can come out when least expected.

Here are some examples of motorcycle valve stems:
http://motorcycle.motorcycle-superstore.com/motorcycle/Tire%20Valve
and....
http://www.motorcycleanchor.com/tire_valves/index.htm

When going darkside it's always better to be safe than sorry.   

[MP]

Tire clearance is only a small part to consider when switching to a car tire on a motorcycle rim.

The biggest and most important safety issue when going darkside is the valve stem clearance and placement which is of utmost importance. Also, they are not all made equal. Using a motorcycle valve stem is the only way to go as the Centrifugal force will pop them out of the wheel when spinning fast.

Another thing to realize is that valve stems on motorcycle wheels are in the middle instead of on the edge like with cars. So they must either be short and straight or short and angled to be able to get air in them. Either way they must be screwed on and seated tightly. If you don't want to change anything then use the same piece that comes with the Valkyrie to hold the valve stem in place or they can come out when least expected.

Here are some examples of motorcycle valve stems:
http://motorcycle.motorcycle-superstore.com/motorcycle/Tire%20Valve
and....
http://www.motorcycleanchor.com/tire_valves/index.htm

When going darkside it's always better to be safe than sorry.   

Sounds to me like he is replacing with mc tires, but just one size larger?

I would think you would be OK alph.  A little taller?

MP

[Hoser]

Tire clearance is only a small part to consider when switching to a car tire on a motorcycle rim.

The biggest and most important safety issue when going darkside is the valve stem clearance and placement which is of utmost importance. Also, they are not all made equal. Using a motorcycle valve stem is the only way to go as the Centrifugal force will pop them out of the wheel when spinning fast.

Another thing to realize is that valve stems on motorcycle wheels are in the middle instead of on the edge like with cars. So they must either be short and straight or short and angled to be able to get air in them. Either way they must be screwed on and seated tightly. If you don't want to change anything then use the same piece that comes with the Valkyrie to hold the valve stem in place or they can come out when least expected.

Here are some examples of motorcycle valve stems:
http://motorcycle.motorcycle-superstore.com/motorcycle/Tire%20Valve
and....
http://www.motorcycleanchor.com/tire_valves/index.htm

When going darkside it's always better to be safe than sorry.   

Sounds to me like he is replacing with mc tires, but just one size larger?

I would think you would be OK alph.  A little taller?

MP

I agree with MP.  Hoser