78XS400 Posted July 2, 2009 Share Posted July 2, 2009 And will a 650 rim/tire fit? I have a 90 on the back right now.... Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 2, 2009 Moderator Share Posted July 2, 2009 And will a 650 rim/tire fit? I have a 90 on the back right now.... tyre wise I've seen a 120 x 80 x 18but it is very close to the chain guard I run 110 x 90 x 18 BT45 on the rear. don;t know about the xs650 as it comes in all sort of guises Link to comment Share on other sites More sharing options...
cafebrad Posted July 2, 2009 Share Posted July 2, 2009 please dont make a wide tire bike. yucko. Link to comment Share on other sites More sharing options...
78XS400 Posted July 3, 2009 Author Share Posted July 3, 2009 please dont make a wide tire bike. yucko. A 90 size tire in the back is not safe at 65 MPH Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 4, 2009 Moderator Share Posted July 4, 2009 A 90 size tire in the back is not safe at 65 MPH not sure what you mean. the speed rating is what you need for safety at speed. 90 is the profile of the tyre. Link to comment Share on other sites More sharing options...
cafebrad Posted July 4, 2009 Share Posted July 4, 2009 not sure what you mean. the speed rating is what you need for safety at speed. 90 is the profile of the tyre. agreed!! the wide tire comment is just my opinion, but thankfully that fad seems to be on the decline. Link to comment Share on other sites More sharing options...
78XS400 Posted July 4, 2009 Author Share Posted July 4, 2009 not sure what you mean. the speed rating is what you need for safety at speed. 90 is the profile of the tyre. What I should have said is that at speeds above 70ish I start to get steering shimmy. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 5, 2009 Moderator Share Posted July 5, 2009 What I should have said is that at speeds above 70ish I start to get steering shimmy. what tyres are you running? Link to comment Share on other sites More sharing options...
78XS400 Posted July 6, 2009 Author Share Posted July 6, 2009 what tyres are you running? Size or brand? 90 in the frt and back Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 6, 2009 Moderator Share Posted July 6, 2009 Size or brand? 90 in the frt and back size, 90 is just one figure. i run 90 x 90 x 18 front and 110 x 90 x 18 rear both BT45 Link to comment Share on other sites More sharing options...
78XS400 Posted July 6, 2009 Author Share Posted July 6, 2009 size, 90 is just one figure. i run 90 x 90 x 18 front and 110 x 90 x 18 rear both BT45 Both my front and rear are 90/90/18 Link to comment Share on other sites More sharing options...
mdsims Posted July 6, 2009 Share Posted July 6, 2009 Both my front and rear are 90/90/18 hahaha, there's your problem! spec for your bike's rear is closest to 110/90-18, If my memory serves me. That is roughly a 2" difference in overall diameter. Effectively, you've changed the final drive ratio of your bike. At 70mph, what do your rpm's look like? Seems like it could be an alignment or balancing issue as well. I'd also suggest using a very small amount of rear brake to help you get out of that wobble zone safely. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 6, 2009 Moderator Share Posted July 6, 2009 shouldn't be any wobble. there's a mismatch of tyres there as mdsims says. also check steering head bearings for notchiness and slackness. what are your tyre pressures? Link to comment Share on other sites More sharing options...
mdsims Posted July 6, 2009 Share Posted July 6, 2009 x2 on checking the bearings. Smaller tires alone won't cause a wobble but they do have an effect on performance, acceleration, rpm ranges (power band), top speed, etc. A 90/90-18 is even small as a front tire. 100/90-18 is where the front should be per spec. Running the smaller front tire is also going to cause your speedometer to be inaccurate. Link to comment Share on other sites More sharing options...
plain old dave Posted July 6, 2009 Share Posted July 6, 2009 Thoughts: -I run a ribbed Cheng Shin 3.00-18 on front and a Cheng Shin K70 3.50-18 copy on back, and the Green Machine tracked like a bullet all the way to Jacksonville and back (@1200 miles on the road). -If you're running a tire designed for the *front* on the back, that will make handling SQUIRELLY to be charitable. The bike will tip in to corners quicker, and won't be as stable on straightaways. Some tires are rounder than others; the K70 is almost square in profile and thus is interchangeable. I know for a fact that Bridgestone Spitfires aren't interchangeable, for one. Link to comment Share on other sites More sharing options...
78XS400 Posted July 6, 2009 Author Share Posted July 6, 2009 hahaha, there's your problem! spec for your bike's rear is closest to 110/90-18, If my memory serves me. That is roughly a 2" difference in overall diameter. Effectively, you've changed the final drive ratio of your bike. At 70mph, what do your rpm's look like? Seems like it could be an alignment or balancing issue as well. I'd also suggest using a very small amount of rear brake to help you get out of that wobble zone safely. Now it all makes sense. My RPMS at 70 MPH are at 6700. Link to comment Share on other sites More sharing options...
78XS400 Posted July 6, 2009 Author Share Posted July 6, 2009 shouldn't be any wobble. there's a mismatch of tyres there as mdsims says. also check steering head bearings for notchiness and slackness. what are your tyre pressures? Pressures are 28 frt and 32 rear. Link to comment Share on other sites More sharing options...
78XS400 Posted July 6, 2009 Author Share Posted July 6, 2009 Guys, I am about to order the correct size tires and need to know if I will need a new inner tube to go from a 90 to a 110 tire?? I dont even know if I have tubes or not, the actual tires say "tubeless" on them so I am assuming that I dont have/need tubes. My Haynes manual says my front AND rear tires should be 3.50 X 18 so the closest to that is the 110/90/18 tire. I just ordered a new one off ebay for the back for $60 shipped. I think I am going to keep the 90 on the front as some websites that list the "specs" for these bikes has the front as a 3.00 inch which is a "90" size tire for the front. Drewpy what size tire do you have on the front? Link to comment Share on other sites More sharing options...
mdsims Posted July 7, 2009 Share Posted July 7, 2009 Guys, I am about to order the correct size tires and need to know if I will need a new inner tube to go from a 90 to a 110 tire?? I dont even know if I have tubes or not, the actual tires say "tubeless" on them so I am assuming that I dont have/need tubes. My Haynes manual says my front AND rear tires should be 3.50 X 18 so the closest to that is the 110/90/18 tire. I just ordered a new one off ebay for the back for $60 shipped. I think I am going to keep the 90 on the front as some websites that list the "specs" for these bikes has the front as a 3.00 inch which is a "90" size tire for the front. Drewpy what size tire do you have on the front? see one of drewps previous posts, he runs the same as you, 90/90-18. That size tire will be fine for the front. I'd suggest getting new tubes every time you change tires. They are too cheap and too important not to change ($6.00/each). As for not needing to run tubes, yes you SHOULD run tubes. The tire may say tubeless but unless the wheel itself says tubeless you need to run them. Tubeless rims are made with different lip shapes to help a tire bead hold on the wheel better. Link to comment Share on other sites More sharing options...
cafebrad Posted July 7, 2009 Share Posted July 7, 2009 maybe a little late but i run a 110/90-18 H rated and it fits fine. Link to comment Share on other sites More sharing options...
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