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Tire Widths

S

slybonesjesse

Sport Tourer
Some background you all know: - Stock front is 120/70-18 on the 94 up, and 110/80-18 on the 86-93. - Factory Dunflop K701 is a 120/70 radial tire designed for a 3.0 inch rim. - The Connie has a 3.0 inch front rim. - The stock tires suck - Many like to replace them with high performance Z rated radials like Avon Storm or Dunlop D205. However these are designed for 3.5 inch wheels. It says right on the Avon site. - Yes that is correct, the killer radials in the stock 120/70-18 size are not intended to be fit on the Connie wheel. The wheel is too narrow. Yet I bet there are a ton of COG riders all out there like this. - The 120/70 is supposed to be 4.7" wide according to Avon. 4.72 according to a tire calculator I used. - The 110/80 is supposed to be 4.3" wide. 4.33 according to the calculator. http://www.avon-tyres.co.uk/motorcycle/storm-2-ultra Getting to the point Somewhere on the old forum a few years back, someone posted that the 110 was going to be the same size as the 120 when fitted to our Connie wheels. I believe this was / had to do with squeezing the tires on a wheel that was too narrow. -- Of course I could not find that thread. This is from crusty ole memory. This was also going to possibly cause the tire profile to be more rounded. I purchased new tires for the Connie as the old D205 are worn. The rear is down the bars and the front is down close to the bars, but has the serious cupping problem people mention. The new tires are Bridgestone BT-45V's and in 110/80-17 for the front, which I am going to mount in the 94 up wheel. On Bridgestone site it says a 3.0" wheel is the widest. So were ok. Curiosity getting the better of me I put the calipers to the new tire sitting on the garage. It measures a tad over 4.33. Just as it should. Then I set the calipers for 4.72 and put them on to the D205 still mounted on the Connie wheel. WOW. Its not that close. Squeeze it down to find its only 4.45" on the wheel. Since I have yet to mount the 110/80 tire, I will have to wait and see if it changes after being mounted. But the D205 is not the 4.72 wide like a 120/70 says on the Dunlop or Avon site. So to me its kinda starting to look like that ole theory I remembered may just be right after all. 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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The new Bridgestone BT-45V in 110/80-18 with the calipers set to 4.33 inches. http://home.comcast.net/~slybones/Concours/images/IMGP5350.JPG The Dunlop 205 in 120/70-18 with the calipers set to 4.72 inches. http://home.comcast.net/~slybones/Concours/images/IMGP5355.JPG 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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All I can say is the Bridgestones will stick like glue where the Avons and Dunlops slide. I'm also very happy with how the rear is not wearing in the center.
 
Love my BT-45Vs "If it hasn't killed me yet, it's runnin out of time" COG # 8062 AMA # 1084053 ROMA or Scarlet harlot acording to my wife
 
Good to hear people like the BT-45's. However the point can apply to any of the tires. A 110/80 Avon Storm z-Rated HP Radial fits PROPERLY on a 3.0" wheel, and according to this theory, would be aprox the same width mounted as the stock 120/70 Avon Storm would be mounted. -- Because the 120/70 requires a 3.5" wheel and is squished on our 3.0" Connie wheel. -- And the 110/80 probably retains the shape profile Avon intended. There are quite a number of guys running the Storm in the 110/80 size on the later year wheels, and quite happy with them. I recall reading this about the widths and so I took the calipers to the tires since I have both at hand, albeit one mounted and one not. 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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I've been very happy with Dunlops on my Connie and previous bike. Currently running 120/80 16 Dunlop Roadsmart Sport Touring on the front and 150/80 16 Dunlop 205 on the rear. No problems on daily commutes rain or shine or carving canyons and twities.
 
The front for the BT-45's came last week. The rear ( shipped separately ) came early this week while the wife and I were off camping at the coast for a few days. The rear on these BT-45V have some serious tread depth. Maybe I just forgot what a new tire looked like. But dang, these are deep. See if I can get a pic tomorrow. 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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I use the Avon Venon Bias tires. I am a pretty agressive rider and they hold well, are good in the rain and last longer then any other tire I have used. Not too expensive from several on-line sites.
 
Sticking with the width part of this conversation, I got the tires mounted today. I took the calipers to them once again. For the 110/80 tire which measured a tad over 4.33 off the wheel, measured 4.33 on the wheel. Pretty much as it should have. Right to the spec listed on the MFG website, etc. For the 120/70 tire which was supposed to measure 4.72, but in reality measured only 4.45 mounted on the too narrow Connie wheel, measured 4.72 off the wheel. That's 0.27 inch change in tire width / profile squishing the tire on the 3.0" wheel. 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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The same two shots above, with three new ones The new Bridgestone BT-45V in 110/80-18 with the calipers set to 4.33 inches. Before mounted, from above. http://home.comcast.net/~slybones/Concours/images/IMGP5350.JPG The BT-45 Mounted. Calipers set at 4.33 inches. Today. http://home.comcast.net/~slybones/Concours/images/IMGP5582.JPG The Dunlop 205 in 120/70-18 with the calipers set to 4.72 inches. Mounted. From Before. http://home.comcast.net/~slybones/Concours/images/IMGP5355.JPG The D205 unmounted loose with the calipers set to 4.72 inches. Shows the before and after for how much the tire gets deformed squishing it on a wheel that is too narrow. http://home.comcast.net/~slybones/Concours/images/IMGP5583.JPG There is the D025 unmounted with the calipers set to 4.45 which is what I measured mounted. I guess its a bit hard to see since I didnt hold the camera perfectly straight on, but the amount that you can see the wheel off on the visible right side, its the same on the left side. I have the calipers centered on the tire. Its aprox .135 on each side. http://home.comcast.net/~slybones/Concours/images/IMGP5585.JPG 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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Sticking with the theme of 110/80 versus 120/70 mounted in a 3.0" Connie wheel. Where the 120/70 HP Z rated radials require a min 3.5" wheel with the Connie 3.0" being to narrow. And a 110/80 is 2.5" recommended with the Connie 3.0" being the widest. And the results above that I measured show my D205 lost some width being squished on the 3.0" wheel. The question is does this also mean as it is squished in on the sidewall its poking out in the middle? According to Avon site a 110/80 is supposed to be 24.8" diameter, and a 120/70 is 24.6". Bridgestone says 24.9" for the BT45 in 110/80. And for reference a 130/70 Wing Tar is supposed to be 25.2" diameter. For many stock tires read a fast speedo. And Wings Tars being larger diameter, rotate slower therefor making the speedo slower, and end up making a inaccurate speedo read accurate, or pretty dang close. -- Do I have that right?? For me, 40K of Wing Tars show that they read slow for me. Confirmed by GPS and WSP. Then I installed the D205's. The speedo was right on the money with the GPS. No WSP verification. -- I am not the only one, but I figured I was one of the few that had an accurate speedo with stock tires. Given the 110/80 is supposed to be .2" taller I was thinking it would read slightly slow. Not as slow as the Wing Tars, but the speedo would be slower than with the 120/70. So today I have the GPS mounted up and out for a trip. I see the 110/80 is actually reading fast, not slow. This seems off the wrong direction. So now I am wondering about squishing the 120/70 on the narrow wheel making it taller diameter, and at the same time wondering in 110/80 on the wider 3.0 wheel ( versus the recommended 2.5" ) maybe make it smaller than the spec. Which combined make if off the wrong direction. 2003 Concours, 63K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm
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