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Rear tires
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newfiedad
Posted 10/16/2005 3:14 PM (#10819)
Subject: Rear tires


Member

Posts: 37
25
Location: St. Croix Falls, Wi
I'm sure it has been discussed, but I can't seem to find it...I have a 1999 Yamaha Royal Star Venture w/ Unitfork front end and a Sauer Sonnenwind beiwagen (sidecar) attached. It is definetly time to replace the rear tire (150/90 B15 M/C74H). I would relly like to mount a flat tread (auto) tire if possible. Does anyone know what will work?? Thanks.
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claude #3563
Posted 10/16/2005 5:33 PM (#10827 - in reply to #10819)
Subject: RE: Rear tires



Expert

Posts: 2471
20001001001001002525
Location: Middleburg, Pa
The 15" motorcycle wheels are too large a diameter to mount a 15" car tire on. It should not be attempted. You could do a wheel conversion which may or may not be econimical to you in the long run which depends a lot on if you intend to keep the bike for a while...or...the Dunlop 491 MOTORCYCLE TIRES HAVE A PRETTY GOOD RECORD OF GIVING GOOD MILAGE FOR WHAT THEY ARE COMPARED TO OTHER MOTORCYCLE TIRES. THERE MAY BE OTHER GOOD OPTIONS AND HOPEFULLY, IF SO, SOMEONE WILL CHIME IN HERE.
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newfiedad
Posted 10/16/2005 5:55 PM (#10829 - in reply to #10819)
Subject: RE: Rear tires


Member

Posts: 37
25
Location: St. Croix Falls, Wi
Thank you for the reply...But if Dauntless sells TwinTires for 16" wheels, which by definintion are larger diameter than 15" wheels, what am I not understanding here?
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claude #3563
Posted 10/16/2005 7:13 PM (#10834 - in reply to #10829)
Subject: RE: Rear tires



Expert

Posts: 2471
20001001001001002525
Location: Middleburg, Pa
You asked about 15" not 16"..what did I miss? Shall we start over ?
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claude #3563
Posted 10/16/2005 7:16 PM (#10835 - in reply to #10834)
Subject: RE: Rear tires



Expert

Posts: 2471
20001001001001002525
Location: Middleburg, Pa
Okay wait..let me expalin futher.
The 15" motorcycle rim is larger than the 15" car rinm so a car tire does not fit properly.
When we go to 16" the motorcycle and car rims are real close to the same size and a car tire can be mounted.
Hope this clears it up some.
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normpottruff
Posted 10/18/2005 12:35 AM (#10866 - in reply to #10819)
Subject: RE: Rear tires


Member

Posts: 35
25
Location: Regina Sask. Canada
Good Day,
Specifically a car 15 inch wheel has an actual tire bead seat diameter of 14.968 inches but a motorcycle 15 inch wheel has a bead seat diameter of 15.080. So a motorcycle wheel is .112 of an inch too tall for a car tire. You could get it on there with enough tire lube, skill, air (never exceed 65 lbs.) and experience but it would mean forcing the car tire onto a rim that streaches the tire a little beyond suggested tolerances. It's been done but every expert will not recommend it. Some folks have approached the problem differently and persuaded a friendly machinist to cut 56 thousandths (.056) off the rim bead seat in a metal lathe. 2 times .056 gives you .112 total height reduction (remember that when you take .056 off one side of a circle you take another .056 off the other side so the total reduction is twice the depth of the cut). This gives you a wheel which should now accept a car tire, however, there may be some slight reduction in the strength of the wheel now due to the bit of metal that was removed from it. As for a tire suggestion, I would go with a 155R15 Vedrestein available online from Tires Unlimited.
Regards,
Norm
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claude #3563
Posted 10/18/2005 7:16 AM (#10871 - in reply to #10866)
Subject: RE: Rear tires



Expert

Posts: 2471
20001001001001002525
Location: Middleburg, Pa
Norm Wrote:
>>Good Day,
Specifically a car 15 inch wheel has an actual tire bead seat diameter of 14.968 inches but a motorcycle 15 inch wheel has a bead seat diameter of 15.080. So a motorcycle wheel is .112 of an inch too tall for a car tire. You could get it on there with enough tire lube, skill, air (never exceed 65 lbs.) and experience but it would mean forcing the car tire onto a rim that streaches the tire a little beyond suggested tolerances. It's been done but every expert will not recommend it. Some folks have approached the problem differently and persuaded a friendly machinist to cut 56 thousandths (.056) off the rim bead seat in a metal lathe. 2 times .056 gives you .112 total height reduction (remember that when you take .056 off one side of a circle you take another .056 off the other side so the total reduction is twice the depth of the cut). This gives you a wheel which should now accept a car tire, however, there may be some slight reduction in the strength of the wheel now due to the bit of metal that was removed from it. As for a tire suggestion, I would go with a 155R15 Vedrestein available online from Tires Unlimited.
Regards,
Norm<<

Norm,
If I may add a little here. The reason we have a hard time recommeneding cutting down a wheel is that it does have the possibility of creating a wheel failuer. Even if there is sufficient 'meat' in the exisiting wheel to make it structurally sound a lot depends on th emacining process being done is such a way as to not induce stress crackes into th ewheel bead after the fact. Work has to be smooth and well done. Also, not all wheels can be machined safey due to various factors of which cannpo tbe defined in all cases. Thickness of the stock bead area is, of course, th eobvious one.
There have been failures reported of machines wheeels. There have also been near disastors reported of tires blowing up,usually at the sidewall, when 15" car tires are mounted on motorcycle wheels.
So, if anyone decided to try either of these things be warned that th eresults are totally your responsibility. Is it worht risking your sdaftey and possibly the saftey of your loved ones to go these routes...??? Let the individual decide for it is not recomended here.
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normpottruff
Posted 10/18/2005 11:20 AM (#10880 - in reply to #10871)
Subject: RE: Rear tires


Member

Posts: 35
25
Location: Regina Sask. Canada
Good Day Claude,
You are correct Claude. I mentioned that any turning should be done by a machinist but I didn't say why. It is important that a modification should be carried out by someone who understands metal. I chat ocassionally with a local chap who's business is repairing damaged car wheels. On some wheels they need to replace a damaged area and then they chuck the whole wheel into a big CNC lathe where it is remachined. If the job is done properly it doesn't seem to be a problem. Ideally a person would have a custom car wheel built of course but I think that if a skilled person is commiting the machining on an existing wheel then I would be comfortable with it. At the same time, nobody is likely to guarantee a modified part, are they?
Regards,
Norm
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claude #3563
Posted 10/18/2005 6:34 PM (#10888 - in reply to #10880)
Subject: RE: Rear tires



Expert

Posts: 2471
20001001001001002525
Location: Middleburg, Pa
One other thing we have found lately is that the motorcycle wheel th eseating area diameters are not consistant from one wheel to the other.I do not know if the standards are different than in th epast or what but before just triming the stock wheel by 'x' amount the thing ahould really be measured to see how much really should be taken off. Maybe this was just a fluke but it has been seem more than once now.
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sidecarLenny
Posted 10/25/2005 7:05 PM (#11097 - in reply to #10819)
Subject: RE: Rear tires


Veteran

Posts: 152
1002525
Location: Warwick NY
Unless you are driving alot miles per year I would go with Claudes rec.
on the Dunlop491, and keep it simple/safe.
Just an opinion.
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claude #3563
Posted 10/25/2005 7:09 PM (#11098 - in reply to #11097)
Subject: RE: Rear tires



Expert

Posts: 2471
20001001001001002525
Location: Middleburg, Pa
And make sure you do not get a K591! Some have done this in error. They are too soft and will not even come close to the 491 for milage. Of course if you change your own tires you will get a lot more practice with the 591.
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