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tire suggestions for '77 GS400

  • Thread starter Thread starter mobius
  • Start date Start date
M

mobius

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Hello,

Currently looking for replacement tires but having troubles finding matching brands to supplement the front (90/90) and rear (100/90) tires. Has anyone successfully put 110/90 on the rear and 100/90 on front?

Any direction is appreciated

Thanks
 
My 450 has 100/90-18 front and 110/90-18 rear on it now. It handles like ****. Tip in feels funky as Hell as does accelerating out of a sharp corner in a low gear.. Ordered the 90/90-18 and 100/90-18 RoadRiders today, I'll let you know how they go.
 
Thanks for the reply tkent02

definitely. Let me know. Did you order online?
 
My vote goes to Pirelli Sport Demon's, awesome tire's and a lot of sizes for our older bikes, a little more pricier than the Avon's though
 
They don't make Sport Demons in those sizes. The 18" front and the 100 width rear makes them a bit hard to find.
Yes, ordered online, American Mototire this time, have all used Southwest Mototire, Dennis Kirk and a few others.
Sometimes buy them off Amazon.

Actually I just checked, Pirelli does make the 90/90-18 front, but the 100/90-18 is only available in a front tire.
Not sure how well it would work using a tire designed for the front on the rear, probably get away with it, but why when there is a perfectly good RoadRider in the correct size made for using on the rear? The Roadriders last a lot longer anyway, they handle great to the end and they are cheaper. They are very nice handling tires.
 
Last edited:
Thanks for the info guys -- I' checked into putting a tire labelled "front", and using it on the rear. Apparently it's not recommended as the tread patterns are directional and specifically designed for either front or back. *shrugs*

I will continue to look online -- I'm in Canada so my options may be a bit limited.

thanks again.
 
How did those Roadriders work out Tom? Shopping for a set of tires myself.
 
Very very good. The improvement in handling was phenomenal. Didn't get to really cornering hard on them, as there was still some sand and gravel around but just going into and out of corners was very much better, the goofy turn in was gone, the squirming when opening the throttle coming out of a turn was gone. It felt like a completely different motorcycle, very solid but very quick, light and maneuverable. Much easier and more comfortable to ride quickly down a twisty road.
 
I'm 100% with Tom on the RoadRiders, love 'em!

I had Sport Demons on my 450 in the larger 100/90 and 110/90 front/rear sizes and I had exactly the same issues with weird turn in feelings. The profile of the front was distorted way too much by squeezing it on the skinny rim.

The 90/90 and 100/90 RoadRiders are just spot on, no more weird tip in feelings and they actually give me what feels like a slightly softer ride on the road.

I'm also getting about 2000km's more out of the centre of the rear compared to the Demons which can also be attributed to being squeezed to the wrong profile on the skinny rim. Unfortunately most of my km's are on the commute which tends to kill the centre of the rear before the sides.
 
And which sizing did you guys use for tubes? Standard size i.e. 300-18, 350-18 or metric sizing.

TIA.
 
While you could probably just go with two 3.50 X 18 tubes, I'd think that in theory a 3.00 on the front would be the right thing to do. I'd rather have a tube a bit small and have it stretch to fit than have it get a fold in it. Basically, if the original size tubes don't fit the tires you're using, the tires are too big.

I have yet to see metric sized tubes. But then maybe I just don't get out enough.
 
I've seen tubes sized at 100-100 and 110-100 thus the confusion on my end. Easy way is just to call. I want this tire, sell me tubes and rim strips. :)
 
Come to think of it why would I need rim strips? It's not a spoked wheel. :-\\\
 
Runeight said:
I've seen tubes sized at 100-100 and 110-100 thus the confusion on my end. Easy way is just to call. I want this tire, sell me tubes and rim strips. :)
Click to expand...

I knew it had to happen. They've come up with an oval tube to go with the low profile tires. :cool:
 
Buying tubes online is a giant pain in the rear because tubes are made of rubber, a substance famous for being stretchy. That means that any given tube will fit a range of tire sizes, not one specific size. Mix in the fact that tubes may be sold under old-style inch sizes, letter sizes, or metric designations, or even all the above, and there are really no e-commerce systems that can cope very well. (This is one product where an old fashioned shop shelf has a lot of advantages over a web site.)

On the plus side, as long as you get the right wheel diameter and you're in the ballpark as to size, you'll be fine.


Anyway, to buy tubes:

- Start with your wheel diameter -- 16", 18", 17", 19", or whatever.

- Then look at your tire width. Don't worry about the aspect ratio. (If you're looking for a 130/90, don't worry about the /90.)

- Then figure out what the closest inch size old-school conversions are for that width. There are charts everywhere. Here's one:
http://www.webbikeworld.com/Motorcycle-tires/tire-data.htm
Notice that just to make this crap even more confusing, front and rear letter and inch size conversions can be slightly different... :mad: Further, notice that most conversions aren't exact.

- Using this information, sift through the available tubes to find a match. For example, on a '77 GS400, the original tire sizes are 3.00-18 and 3.50-18. This translates to 90/90-18 up front and 100/90-18 out back.

American Moto Tire is probably the clearest in their descriptions, so we'll use them as an example (they're a great vendor):

Notice that the correct tube for the front supposedly covers widths from 2.75 to 3.60.
IRC TUBE 2.75/3.60-18, 90/90-18, TR-4
http://www.americanmototire.com/catalog/product_info.php?cPath=610_615&products_id=2349

This tube would stretch to work for the rear as well. This would be a good choice for a spare tube to carry on the bike, since it would fit either end.

However, there are two other IRC tubes available that could also work for the 3.50-18 rear:


This one is listed as covering 3.25 to 4.10: http://www.americanmototire.com/catalog/product_info.php?cPath=610_615&products_id=2350
This is the one I would buy, since 100/90-18 is just a teensy smidge smaller than 3.50

This one just lists 3.50 - 4.00: http://www.americanmototire.com/catalog/product_info.php?cPath=610_615&products_id=2352
 
i just picked up a 1977 GS400 that has a 100/90 R18 on the front and a 120/90 R18 on the back....Bridgestone Spitfires....
 
It will ride like crap with those sizes especially with old design tires like those.
.
 
bwringer >

I have ordered from AMT and agree. Thank you for the detailed reply. Sums it up for me and anyone else.

Since I lean towards originality I'm still on the fence. Plenty of time to decide.
 
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