450-18

Has anyone fitted these to there XS400. mine is a 77 model and im curious if the clerance between the forks will be a issue. i would like to go 500-18 tyres. i have to order them as no shops around me stock them, so i cant try them.

http://www.antiquetyres.com.au/18450-0

AMR-XS400 said:

Has anyone fitted these to there XS400. mine is a 77 model and im curious if the clerance between the forks will be a issue. i would like to go 500-18 tyres. i have to order them as no shops around me stock them, so i cant try them. http://www.antiquetyres.com.au/18450-0

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I've never tried anything like them, but it seems to me the critical spec to ask the supplier before ordering them is the "overall width", and, if this measurement is greater than "section width". The 450 tires you linked to have a section width of 4.84". So if your forks are not at least that far apart they can't fit.
According to the chart and 2 definitions below, overall width could be slightly greater depending on if the tire moulds include ribs or decorations on the sides - but not necessarily. Good luck.

There may be a safety issue here. Your front wheel is probably a 1.85 rim width and the rear is probably a 2.15 rim width. A 4.50 tire will be severely deformed when mounted on the narrow wheel. Others will chime in I am sure.

Old Okie said:

There may be a safety issue here. Your front wheel is probably a 1.85 rim width and the rear is probably a 2.15 rim width. A 4.50 tire will be severely deformed when mounted on the narrow wheel. Others will chime in I am sure.

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Very good point, I completely missed considering that. Unless you are fitting different wheels with 4.5" wide rims, O-O is right.
If not, here is another thread where Jacob got a pretty nice look while staying within the parameters of the rim sizes:

well, i have just checked the stamps on my rims and both are 2.15x18. i then tried the 400x18 rear tyre i have on it at the moment up front and it won't clear the forks, go figure?