New tyres for GS400

[maclariz]

Dear all,
I need to replace the tyres I have on my 1978 GS400 pretty soon and need some help.
The bike is one with spoked wheels and the old tyres are Avon Roadrunners in 90/90 R18 front and 100/90 R18 rear.
So, do I need tubed or tubeless tyres?
What are the official tyre sizes for this bike anyway?
Tyres that match the existing sizes are pretty thin on the ground. At the moment I can find Avon Roadriders in these sizes and nothing else. If I went up on width slightly to a 110/90 R18, I could get a BT45 or some other tyres to fit the rear.
What brand/exact tyre model would you recommend?

Thanks

Ian

[tkent02]

Avon Roadrider is far far superior to the BT45.
Go with it.

[Nessism]

I ran 100 in front and 110 in back on my old 450. Seemed to match the bike well.

[earlfor]

You can use either tube or tubeless type tires, but with spoked wheels, you will have to put tubes in them.

Earl

[Steve]

Larger tyres? How wide are the rims? Unless your rims are wide enough to support the wider-width tyres, you may want to stick with the stock size or just one size over. Nessism's use of the 100 on the front and 110 on the rear would probably be as large as you would want to go.

.

[Suzuki mad]

In the UK tyre fitters will not fit a tyre to old bikes without a tube in. The wire wheeled GS400 would have been tubed so run with it.

Suzuki mad

[maclariz]

Thanks for the replies:
So I run with a tube in.

No answer to one of the other questions though. Anyone know what size of tyre is actually recommended for this bike? My Clymer manual is pretty useless when it comes to general specs for the bike..... It just tells me what pressure to pump the tyres to.

I'm happy to stick with the current tyre sizes if that's the best, but I wondered if anyone has some more accurate information.

[maclariz]

Why is it better?

Avon Roadrider is far far superior to the BT45.
Go with it.

Why? What's better about it? Performance in the wet? Performance in the dry? Tyre wear?

[bwringer]

Why? What's better about it? Performance in the wet? Performance in the dry? Tyre wear?

All of the above.

[Steve]

No answer to one of the other questions though. Anyone know what size of tyre is actually recommended for this bike?

I just did a quick search and found that the '77 400 came with a 3.00-18 on the front and a 3.50-18 on the rear, I would assume that your '78 would probably have the same sizes. Since all of today's tires are using metric sizes, that would be about an 80/90-18 for the front (a 90/90-18 would probably cure any speedometer error) and 90/90-18 for the rear (a 100/90-18 might be easier to find). Since those are the sizes of the Avons you have on there now, you already know they will fit, but please note that your current tyres have an R in the size. That indicates that they are radial tyres. The rims on these bikes are not set up for radial tyres, and I would recommend sticking with the stanadard bias-ply.

.

[KamakaziDude]

If you have a chrome front fender you need to look at how much clearance you have between the top of the fender bracket (at the point where it connects to the fender) and the side wall of the tire. If it's already a tight fit I wouldn't go with a tire any wider than you currently have.