Tire sizes

Having trouble locating tube type tires for my 78 gs550 (spoke wheels). The manual says to use 90/90-19 front and 110/90-18 rear. What other sizes, if any, can I use?

Most tubeless will say tube/tubeless on them. There are plenty tire size calculators. Google is your friend!

A lot of manufacturers have the recommended rim width under their tire specs. Take a look at those to get an idea. Generally though, 1 size over is OK. 2 sizes over and the tire profile can change which is really not good.

Early GS bikes came with tubed tires and Birdgeston list Tubed and tubeless tires in those sizes IIRC. Some of the later GS wheels were Tubeless.

I want to say that crossed spokes had tubes and bent spokes were tubeless but that may not be 110% accurate.

I have a set of 78 crossed spoke/snowflake wheels that do need a tube because the rim is different to later tubeless rims. Tubeless have a taller bead retaining ring.

I just checked http://www.bridgestone.com/products/motorcycle_tires/products/battlax/bt45.html and they list only two TT (tube type) tires and one is 100/90-19 which is a little wide but would work. The rear should have a 110 or 120. They do list a 4.00 TT and it's almost teh same as a 120 and should work fine on your rims.

In fact I will need to order a pair of those for a GT750 that has GS wheels on it.

Awesome, thanks for your help! Will be ordering some tonight

You can also use tubeless tyres (with tubes) on tube type rims - you don't have to use tube tyres exclusively.