• Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Tire and Rim Size

Kenneth Webb

Kenneth Webb

Livin' It Up!
I have several size new D606 tires in the garage along with a new 140-80 18 Heidenau K60, ready to spoon on. I notice that the K60 appears to be made for a wider rim than the 2.15 which is stock on the 630. Looking on the net I find this http://www.mtsac.edu/~cliff/storage/gs/Motorcycle_Rim_Width_Tire_Size_Chart.pdf which shows that a substantially wider rim is recommended. The minimum shown is a 2.75 and the "std" is a 3.5. Even the smaller 606's are made for wider rims than on either the 630 or my 250. Both bikes have the same size rims front and back; 1.6 front and 2.15 rear. When I squeeze the K60 to 2.15 it distorts the 140 carcas quite a bit. I've asked the importer for Heidenau's recommendations, but wondered if anyone else has had this question and found an answer. Why are our rims so narrow!
 
Tire voodoo.

I have 3 bikes with the same 2.15" rear rim and all recommend a different size tire.
spec ; mounted
TE630 - 140/80-18 ; 130/80-18
KDX200 - 5.10-18 ; 4.00-18 trials
300EXC - 110/100-18 ; 110/100-18

2.5" inch rim
DR650 - 120/90-17 ; 5.10-17

Adding to this every manufacturer's tires differ considerably even for the exact same stamped size. Of all the tires above when I take an actual caliper measurement of the tire width guess which is the widest? 110/100 is by about a quarter of an inch. So except for the trials tire what should be the narrowest tire turns out to be the widest.

_
 
I am going to assume that bike tires are designed the same way as auto tires. Each tire is designed to work on a certain size rim, plus or minus, to keep the profile and contact patch within the design perameters. Using too narrow a rim will pull the sidewalls together and make the center part of the tire project "more". On autos you will either get too much wear in the center or too much on the sides when you use the wrong rim width. Perhaps dirt bike manuf. want this effect, but I don't know. Most tire manuf. don't seem to publish a specified rim for their tires, but the ones I did find show a wider rim for the 140 than is on the husky. I'm just very curious....
 
I think the 2.5 is the way to go, and if I ever have Woody's lace up a new rim on a cush hub that's what I will get. It means not using the Tubliss though, and I really enjoy not having to break down the tire when I have a flat.
 
I have a question in to Woody's Wheels on the rim size. Looking at his tire and rim charts, we definitely have rims that are too narrow for the appropriate tires. The rear should be 3.5! And the front should be 2.15, the same as our rear right now. It's a real puzzlement to me. If Woody comes back confirming this, I will change out my rear rim, and perhaps the front, in the interest of getting the tire profile correct where it meets the ground. Maybe we will even get some extra mileage from our rubber, but that is a guess.
 
I think the answer may be that the rim width chart above doesn't differentiate between wheel diameters or street vs. dirt tires. A 140/80-17 street bike tire would require the indicated rim, a 140/80-18 dirt tire is designed for a narrower rim. I don't think Husky's engineers or the product liability dept could have missed something this big. I'm curious to hear Woody's answer.


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DYNOBOB said:
I think the answer may be that the rim width chart above doesn't differentiate between wheel diameters or street vs. dirt tires. A 140/80-17 street bike tire would require the indicated rim, a 140/80-18 dirt tire is designed for a narrower rim. I don't think Husky's engineers or the product liability dept could have missed something this big. I'm curious to hear Woody's answer.


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Click to expand...
what he said, I will not change rim sizes unless I go to SM wheels.:eek:
 
Ken, you've discovered an area that is not widely understood by most of the riders. Nor do they care. But yeah, tires are made for varying rim widths. I suspect the 130 K60 is a much better fit for the 630. I know the TKC 130 is a quite large looking tire, at least in 17".

The true knobby types, like the 606, will squeeze on better than a more road-going tire.

The bigger bikes have wider wheels, and then they have the opposite problem with tires not being wide enough.

The 3/8" diff from 2.15 to 2.5 is probably indescernible.
 
I looked at a friends DR650 this weekend and he has a 2.5 on the rear. Woody is thinking that a 2.5 on a dirt bike is probably OK, but still, you have to really squeeze the Heidi to make it fit. I had just never thought about this until I looked at the unmounted Heidi and the D606 side by side. The Heidi really wants a 3 or 3.5 to maintain a decent profile. Same for the 606 although the sidewalls are much more flexible which makes putting them on a narrow rim easier. One minor issue for me is that I like the Tubliss system, and you must not go over 2.15 rim width for that to work. I'll give that up though, when I re-lace, and go to wider rims. 'Looked at a pic of a big KTM and they have WIDE rear rims! They are set up for road going tires though, and we just don't need to do that. The widest Excel Takasago rim in 21 is 1.6, which we have. The widest 18 is 2.5. Is it worth changing for an extra 0.35 of width? If I decide to run Heidi's, I'll probably do it.

Hey, everyone has to have some nonsense to worry about, right?
 
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