Tire recommendation for 1977 GS 400

[Guest]

Hey all,

Just picked up a 1977 Suzuki GS400 and it's pretty clean.

I have to replace the front and rear tires, however, I am finding it difficult to source a matching set of 90/90-18 (Front) and 100/90-18 (Rear)

I reside in Canada and have tried local shops along with https://www.canadasmotorcycle.ca/ with no luck.

Any chance you can run 100/90 on the front rim? If not, any recommendations on brands that do have this combination?

Thanks for your time.

[Who Dat?]

I can't offer any recommendations for brands in those sizes, but you should be able to safely move up 10mm on each tire, looking for a 100/90 on the front and a 110/90 on the rear.

Motorcycle Superstore has several choices in those sizes. There are other suppliers, might have to shop around a bit to make sure they will ship them north.

[bwringer]

Original is 3.00-18 front and 3.50-18 rear, which convert to 90/90-18 and 100/90-18.

As you're learning, most 100/90-18 tires are fronts, and the 90/90 is a little hard to find. But it really is worth seeking out the correct sizes to enjoy the nimble, balanced handling these bikes are designed for.

About the only modern tire I'm finding is the Avon RoadRider. The 100/90-18 can be used on either the front or the rear. A lot of online catalogs have trouble correctly listing these front/rear Avons (they're often listed under front only or rear only), so perhaps that might explain why you can't find them.

A great site for researching (and ordering) weird tires is http://www.americanmototire.com/ . They have a fantastic "search by size" widget on the left. I have no idea whether they ship to Canada, but maybe this will help you at least figure out what's available in North America.


Another option would be to order tires in the original inch sizes. You can still get the IRC GS-11 (which is the same or very close to the original tire used on this bike), the IRC NR21, and a couple of dual-sport tires in 3.00-18 and 3.50-18.

[Stuarth]

Conti makes a Conti Go! in 90/90-18. I bought a set for my Yamaha SRX600 and am happy so far. The matching rear is available in 100/90-18 as the smallest size which should work fine for you. It may raise the rear of the bike a bit though, which would make your bike lean over further on the side stand. My SRX takes a 120/80-18 rear so I went with the 110/90-18 rear. It raised the back of the bike about 1/2". I wasn't comfortable with that much change on my SRX as it already leaned over a fair a!ount on the side stand, so I bought a spare stand for mine and had a short extension welded onto it to compensate. This way I have an option to go back to the stock (shorter) 80 series if needed.

[tkent02]

Conti Go, good to know.

OK just looked, the front 90/90-18, no problem. The 100/90-18 for the rear is a front tire also. Probably get away with it on the rear of a low power machine like the 450 but I'd rather not if it's possible not to.

[tkent02]

Nevermind, just ordered the RoadRiders.

[bwringer]

Conti makes a Conti Go! in 90/90-18. I bought a set for my Yamaha SRX600 and am happy so far. The matching rear is available in 100/90-18 as the smallest size which should work fine for you. ...

No, as tkent found, the 100/90-18 Conti Go! is a front tire, not a rear.

[Nessism]

I put Conti Go's on my KZ750E and like them. It's too early to judge mileage, but they steer really nicely on my bike; the bike leans easily and stays leaned over without any tendency to stand up or fall into the corner. They seem a little narrower for their stated size compared against some other tires.

[John Park]

Hey all,

Just picked up a 1977 Suzuki GS400 and it's pretty clean.

I have to replace the front and rear tires, however, I am finding it difficult to source a matching set of 90/90-18 (Front) and 100/90-18 (Rear)

I reside in Canada and have tried local shops along with https://www.canadasmotorcycle.ca/ with no luck.

Any chance you can run 100/90 on the front rim? If not, any recommendations on brands that do have this combination?

Thanks for your time.

The original tires specified were tube type , 3.00 - 18 front, and 3.50 - 18 rear. This is more or less equivalent to the sizes you mentioned. However, you can still get the original sizes, and they're quite reasonably priced at canadasmotorcycle with free shipping ad a second tire discount.

Duro HF 308 3.50 x 18 $53.65 and Duro HF 317 3.00 x 18 front $45.89.

These tires are similar to the IRC GS11 with the HF308 rear being a lot deeper tread and longer lasting. The IRC is dead silent but the Duro hums a bit, if you listen for it. The tread is pretty shallow on both fronts, but the wear rate is pretty low so you just replace both at the same time and keep the rubber fresh.

The Avons are probably the best choice if you feel more confident using 'modern' tread patterns. On a light bike the reduction in tread squirm isn't that noticeable unless you're near the limits.

Don't let the low prices for the Duros scare you off; I've hammered them pretty hard and they've exceeded my expectations.

[mobius]

bwringer, Stuarth, John Park, Nessism


Appreciate the detailed response -- I will look into my options here and let you know how it goes.


Do you guys typically install the tires yourself of did you take them to a mechanic?

[tkent02]

I do them at home. They want ridiculous money per tire, I do many sets of tires per year. It takes longer to drive them down there than it does to dismount and mount the tires. Then there's always the thing about inspecting the wheel while it's apart, putting in a new tube or a new valve stem if it's required, checking the wheel bearings, etc....

The other thing is that the more tires I do the easier it will be when my dirt bike takes a puncture in the rain at night miles from the trailhead with only the tools I carry. It's really pretty easy once you get a good technique working.

[mobius]

I do them at home. They want ridiculous money per tire, I do many sets of tires per year. It takes longer to drive them down there than it does to dismount and mount the tires. Then there's always the thing about inspecting the wheel while it's apart, putting in a new tube or a new valve stem if it's required, checking the wheel bearings, etc....

The other thing is that the more tires I do the easier it will be when my dirt bike takes a puncture in the rain at night miles from the trailhead with only the tools I carry. It's really pretty easy once you get a good technique working.

Thanks tKent02 - Do you know of the there is a tutorial on these forums regarding the changing of rubber?

[tkent02]

Come to my house and watch, I'm putting the new Roadriders on the 450 and putting the studded knobbies on the DR today.

Actually this one is good:

http://advrider.com/index.php?resources/tire-changing.56/

[John Park]

While we're here, I'd like to mention that the steel rims on these bikes had a propensity to rust. Even if the outside looks pretty good, the moisture would go down the spoke holes and the spoke well would get pretty funky. It's not usually a structural factor, but flakes of rusty chrome can work their way around and puncture a tube sometime down the road. They also used some sort of machine to tighten the nipples, and I've seen the end of the nipple slot twisted up to a point and puncture the rim strip and then the tube.

So the chances of a thorough inspection and service of the rim probably won't happen at the shop. They'll take the usual attitude of 'it held air before, so it will again'. Unless the bike lived in a really dry place, you'll have to take a wire brush and get any loose rust off. I also like to take a file and make sure the nipples don't have any sharp edges poking up. In all probability, the rim strip will be ancient; you'll also need a new tube - keep the old one for a spare.

Spin the wheel bearings to see if they're smooth. You can pry the dust covers off the bearings and pack some fresh grease in. Removing the 20th century grease first is nice, but by that time you're probably best just fitting new bearings; you'll destroy them taking them out and they're cheap.

Being able to service your own wheels and tires is empowering. In theory, bike shops should take a very serious attitude towards tires and wheels, but often the shop flunky gets to do it because the journeyman is in the middle of some major rebuild and can't be bothered. I've seen so many horrors that should never have happened. So, even if it's your first time, at least you know you're sober and care about what you're doing and your mind isn't on something else. And you're not in a hurry.

[tkent02]

While we're here, I'd like to mention that the steel rims on these bikes had a propensity to rust. Even if the outside looks pretty good, the moisture would go down the spoke holes and the spoke well would get pretty funky. It's not usually a structural factor, but flakes of rusty chrome can work their way around and puncture a tube sometime down the road. They also used some sort of machine to tighten the nipples, and I've seen the end of the nipple slot twisted up to a point and puncture the rim strip and then the tube.

So the chances of a thorough inspection and service of the rim probably won't happen at the shop. They'll take the usual attitude of 'it held air before, so it will again'. Unless the bike lived in a really dry place, you'll have to take a wire brush and get any loose rust off. I also like to take a file and make sure the nipples don't have any sharp edges poking up. In all probability, the rim strip will be ancient; you'll also need a new tube - keep the old one for a spare.

Spin the wheel bearings to see if they're smooth. You can pry the dust covers off the bearings and pack some fresh grease in. Removing the 20th century grease first is nice, but by that time you're probably best just fitting new bearings; you'll destroy them taking them out and they're cheap.

Being able to service your own wheels and tires is empowering. In theory, bike shops should take a very serious attitude towards tires and wheels, but often the shop flunky gets to do it because the journeyman is in the middle of some major rebuild and can't be bothered. I've seen so many horrors that should never have happened. So, even if it's your first time, at least you know you're sober and care about what you're doing and your mind isn't on something else. And you're not in a hurry.

+1, What he said.