Dunlop K81s for my 78 CB400T

[83CM250C]

Due to selection/availability I'd like to run Dunlop K81/TT100 front and back on my 78 CB400T II. Only twist is factory front spec is 3.6X19 and my availability is 4.1X19. Appears to be plenty of room for it there; my only concern is that the Comstar rim is stamped 19x1.85. The "guideline chart" of rim sizes/STD tire sizes I was provided in here even shows the factory tire size to be wider than acceptable width. My feeling is that it should be fine (running tubes here). Are people running 4.1X19 on old comstar tube type rim (19x1.85)?

 

[Boosted]

Didn't know or expect any Comstar alloys to require innertubes... ..No tubes needed on those of my '82s... ..and, even though Dunlops are Made in the USoA, I went with Shinko 712 tires, partly because in my tire research for my '82s, I learned Shinko acquired Yokohama which was THE Honda factory supplier of OEM tires back when my motorbikes were new...

 

[LongDistanceRider]

The early ComStar wheels are tube type. There's barely, if any, inner bead safety ridge.
The odd numbering 3.60 and 4.10 mean they are 80 profile tires instead of the usual 90 profile for numbering like 3.50, 4.00, etc.
You should be fine running the 4.1 but a 3.50s19 would be better. Fatter tires do not increase grip, sometimes the opposite occurs.

 

[ballbearian]

The early ComStar wheels are tube type. There's barely, if any, inner bead safety ridge.
The odd numbering 3.60 and 4.10 mean they are 80 profile tires instead of the usual 90 profile for numbering like 3.50, 4.00, etc.
You should be fine running the 4.1 but a 3.50s19 would be better. Fatter tires do not increase grip, sometimes the opposite occurs.

Take Jim's recommendation, he knows. I put 4.00H 18 and 3.50-19 ribbed front, both Duros because I already had the rear but they are a bit too pudgy and raise the bike some , no doubt. My 78 type II two has the tube types.

 

[83CM250C]

Thanks guys so I have the Dunlop K81s as a readily available option, though they are a little pricey. I'm going to try to consider others (e.g. Shinkos) too. My suppliers will crossreference from the old sizes to the metric, or is there a table available for that? I know how to multiply by 25.4 but would be more comfy with less guessing (and I'm not seeing any 90mm width 19" Shinkos).

UPDATE for others that could be interested:
Supplier says 4.10S18 converts to 110/90/18
Supplier says he doesn't have exact conversion for 3.60S19 but 3.50 converts 100/90/19
Other supplier says 3.60-19 is closest to a 90/90-19 or 100/90-19

Great, I'm all set, have a new enough old stock 100/90/19 Elite for the front and good selection of 110/90/18 available for rear

 

[ballbearian]

Thanks guys so I have the Dunlop K81s as a readily available option, though they are a little pricey. I'm going to try to consider others (e.g. Shinkos) too. My suppliers will crossreference from the old sizes to the metric, or is there a table available for that? I know how to multiply by 25.4 but would be more comfy with less guessing (and I'm not seeing any 90mm width 19" Shinkos).

UPDATE for others that could be interested:
Supplier says 4.10S18 converts to 110/90/18
Supplier says he doesn't have exact conversion for 3.60S19 but 3.50 converts 100/90/19

Great, I'm all set, have a new enough old stock 100/90/19 Elite for the front and good selection of 110/90/18 available for rear

Running tubeless tires with tubes works but lowers speed rating 10mph, IIRC.

 

[Boosted]

You may not be seeing or finding exactly what you're looking for, neither did I, sort of... ..But before I/we add any more confusion/despair, I should say that my 1982 tubeless-ComStars are differently sized : my front wheel is 18" in diameter and my rear is 16"

Also: describing tires as having a "90mm width" isn't technically correct - the 90 number is a tire's "profile" or part of a ratio best described/explained as this: My rear Shinko tire is a 130/90-16. Its width is calculated as being 90% of 130mm which equals 117mm

Further, I too had to cross-reference my tire sizes from the old way (my front = 3.50, my rear = 4.60) into the modern way and yes, there are table(s) you'll likely find with a "search" of this VHT forum, or they're also at most if not all of the tire manufacturers' websites too...

Lastly, (in case you weren't already aware) motorcycle tires are made specifically for either the front of a bike or the rear of a bike. There's several reasons why and they all factor into safety.

"LDR"-Jim informed me of the European tire manufacturing company Heidenau which I considered yet forgot to mention in my tire purchase post within my "Project" thread. Part of why I bought the Shinkos was because of both his and "Ancient Dad"-Tom's approvals/recommendations, yet choosing the 130/90-16 (instead of Heidenau's 120/80-16) for my rear involved having to re-position the rear brake's actuating rod (between brake pedal and brake drum) so to clear and not rub constantly the wider width of the 130/90 (which may or may not apply to your '78 400, if it that's even possible on your bike) - Jim should know...

 

[LongDistanceRider]

The only repositioning I'm aware of is when a 130/90/16 tire is used, the rear brake stay(arm) needs to be moved outboard of it mount on the swing arm. The CB400/450 series uses an 18" rear and a 120 fits w/o repositioning the stay, not that a 120 is a good fit for the wheel(it's not).