Try ECS they can probably tell you

 

Both are listed at 16.5 kg
7P6 601 025 AG AX1 9J x 20H2 ET57 MALLORY shiny black
7P6 601 025 AK 88Z 9.5J x 21H2 ET59 MALLORY

 

Both are listed at 16.5 kg
7P6 601 025 AG AX1 9J x 20H2 ET57 MALLORY shiny black
7P6 601 025 AK 88Z 9.5J x 21H2 ET59 MALLORY

I really appreciate it buddy... Thank you so much

 

I find it difficult to trust that they would both be the same weight....

 

Good catch.. I didn't even realize that.

 

The difference would a matter of tens of grams between the same wheel in 20" versus 21".
I am not going to debate this subject all I am offering is the technical specifications that I have access to.

 

I understand what you are offering, however what I am saying is true. I don't know how significant the difference will be, but it will be more than a few grams. You're adding 1/2" to each spoke and another 1/2" to the barrel.

I'd guess it would be closer to .5 Kg but don't have access to parts to provide any data.

 

My guess is that the 21 inch wheel will be about 5% heavier due to 5% longer spokes and 5% long rim circumference. So maybe 700g to 800 g heavier. The overall wheel and tyre assembly will be less different as 21 inch tyres with the same O/D and lower side wall will be lighter

 

The maths makes sense, you forgot to say that it is also 5% wider, now if the load rating of the two is the same that would make it likely that there are no manufacturing imput differences in raw materials used to make the two.

TonyB