ZEPHYR550/400 Pondering tire types (*´ω`*)

Unusually for bikes I’ve owned before,
the front is 17 inches and rear is 18 inches.

I initially considered going with 18 inches up front too, but that seemed wasteful.
You can only experience the stock character while it’s stock (*´ω`*)

I want to choose tires based on the wheel size.

First, let’s check the tire and wheel sizes for the Zephyr 550/400.

Front wheel 2.50-17, tire 110/80-17
Rear wheel 3.50-18, tire 140/70-18

These are quite narrow tires, so the handling should be light and fun ♪
For city riding, aside from tire size options,
I think thinner tires are more enjoyable.

Next, let’s understand the numbers from tire sizes

I’ll reference the BT46.

110/80-17 M/C 57V TL

2.50

2.15～3.00 Recommended rim

609 outer diameter

110 width

140/70-18 M/C 67V TL

4.00

3.50～4.50 Recommended rim

657 outer diameter

143 width

Here I’m mainly paying attention to the “recommended rim size” and the “outer diameter.”

Not just the stock tire size, but
the “recommended rim” and the “tire size” that goes with it.

Of course, the outer diameter is also very important, so pay attention to that.

The 2.50-17 front tire has plenty of options,

The rear is a bit problematic.

For a rim width of 3.50,
“140/70-18 uses a standard rim of 4.00,” so
the tire shape is slightly deflated.

“A wider tire on a slightly narrower rim”
causes the edge to roll in a bit.
*No issues within tolerance.
“130 size is also a viable option” in terms of sizing.

“140/70-18 has an outer diameter of 657”
I’d prefer not to change the bike’s stance too much

130/70-18 M/C 63H TL

3.50

3.00～4.00

644 outer diameter

135 width

If I were to choose the BT46’s 130/70-18, the outer diameter would be -13MM. Half of that means the rear drops -6.5MM.


A -6.5MM change is like
“tires that have worn down quite a bit” or “underinflated tires.”


As tires wear, the change becomes more pronounced, so I’ll exclude options that lower the stance.
*Reversing the eccentric might be an option too…

130/80-18 sounds interesting, but…

130/80-18 M/C 66V TL

3.00

2.50～3.50

665 outer diameter

128 width

I’m struggling with the limited options for this 130/80-18 size.

The Conti RoadAttack 3 matches front and rear,
but I’m hesitant about availability and price.

Maybe this deliberation is the most fun part?

(*´ω`*) In the end, METZ Z8M INTERACT