Im getting a new rear tire this week. I was told today at a metric dealer, that the 404 is a standerd Bias ply and the 401 is reinforced with 2 fiberglass belts. He said the 404 is a bit softer tire and rides a little smoother over sharp bumps, but it's more narrow then the same size 401, but not by much. He also said the 404 could be more dangerous if it suddenly goes flat at high speeds because it's not reinforced. But the 401 is a harder tire and don't take the sharp bumps as smooth, but they should last longer and are safer.
I can get the 404s for about $50 less. Im not buying the tires from them, but they know me at this dealer. If all this is true, then I think the 401 is worth the extra $50. I don't like the sound of the 404 not having reinforced belts, or the narrow thing.
So was this guy stright-up with me ?...

 

Yep, that's pretty much the straight scoop. I surprised, because most dealers can't tell you what the real differences are between the 401 & 404. For me, I don't like the price but I want belted tires. just my .02

 

I have one of each I am workingon now. A 404 on the super glide and a 401 on the sportster. Handling wise they are the same IMO. However, the 404 does have less tread then the 401. I think the 401 is 12/32 and the 404 is 9/32. Yes, I do think you will get more miles out of the 401 because it has more tread. However, the 404 is a VERY underated tire. I think people hate on them because they are very inexspensive, are jap made and have a little less load capacity. I do hate jap products in general, but I think the 404 is a good tire. The metric owners all run 404s and they are stock OEM from Honda. They are a good tire just a older design.

 

I've been trying to do as much reading as I can about 404's v 401's.
There seams to be a consensus that the 404 won't last as long. (One season maybe) But I like a new tire each season anyway.
The 404 is slightly softer and may stick better when cornering.
I don't have a large heavy touring bike, where the reinforcing and the longevity of the 401 would be an advantage.
I hate to 'Go Cheap on Tires' but the 404 is stock on most rice burners.
I only have my Sporty..I think it would be fine.
I am going to try the 404 as its just over half the price of the 401. I will see if it a false economy.

 

Got these specifications from a full size Dunlop catalog.
Size: 100/90-19 front
D-404
width: 3.90"
OD: 25.82"
thread depth: 6/32"
max load: 407#@41spit
Note: "designed for smooth ride for maximum comfort"

D401
width: 3.95"
OD: 26.45"
thread depth: 6/32"
max load: 407#@41psig

Size: 150/80-16, rear

D404
width: 5.81"
OD: 25.35"
thread depth: 9/32"
max load: 761#@41Sig

D401
width: 6.15"
OD: 25.45"
thread depth: 10/32"
max load: 761#@41psig
Could: "use bias or bias belted construction" (Which tire is belted)?

Tire manufacturers do not specify durometer hardness of rubber compound,
but the hardness increases in the tire with time, even in a tire warehouse starting from the birth date of the tire.

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