Project SiR The Bicycle Pages Project Yamaha RD400F


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Kosei Website

Kosei K1 Racing 16x7.5" 43mm Offset

The Kosei K1 Racing wheel is one of the most popular wheels on the market for the budget-minded amateur road and autocross racer. These wheels are made in Japan, and at 15 lbs. are reasonably light for a 16x7.5" wheel. As a comparison the stock SiR 15x6" wheel is 16lbs, even though it is 1" smaller in diameter and 1.5" narrower.

Through internet research I found out that these wheels do not normally come with centre caps, so I made sure to request them when I ordered them from Steelecase Tires 'n Mags. What these wheels do come with are blingy anodized blue valve stems and caps (two caps stolen within two months of putting them on), and a set of light weight lug nuts. I added a set of light weight wheel locks to go with the lug nuts, as some people have had problems when using "regular" locks with light weight nuts due to the imbalance. I would not have thought such a small difference in weight would make a difference, but apparently in some cases vibration can occur.

I had one fitment problem when installing on my 1999 Civic SiR in that the rear rim brushed up against the knuckle on the upper arm of the rear suspension when the suspension was loaded (see bottom of page for image). Not good, as left unchecked the rubbing would have ate through the rim. Some quick work with a grinder and some spray paint to protect the resulting bare metal did the trick. Other than that, there has been no rubbing there or anywhere else either at stock ride height or when lowered 1.25".

Overall a strong, light, inexpensive, and IMO a good looking wheel. Can't ask for much more than that.

Right: upper suspension arm knuckle highlighting area where wheel rubs under compression. This shot was taken when only a little bit of the knuckle was grinded down for clearance. Further grinding was required to make sure no contact was made, then spray paint was used to prevent corrosion.