DIY: Screw Tires - Choosing tires and screws

Mar 4, 2008 at 11:21
by Janne Aspinen  
This is part of my article "DIY: Screw Tires".

Check it out here.Choosing tires:


1. Compound

Tires should be some compound that doesn't harden up, when it's cold.
Very soft compounds from varioius brands turns to like plastic in cold.
If your tires turns to plastic, they dont have any traction on them.
There is difference in between brands. All I know is Nokian is pretty
safe choice, especially Gazza G and NBX with their normal compound
should be fine.

If you are worried about your tires, keep them in cold for some time
and check what happens.

1811362

1811362

I chose to use proven Nokian Gazzloddis.


2. Size

When running on screw tires, normally we use quite high pressure in
tubes to avoid punctures. If you run 2,5" tires normally, you can
run 2,3" in winter. It doesn't make so big difference. Very important
thing to remember is clearance. When you have screws sticking out from
your tires, it will add quite a bit to width and height.

My Gazzaloddis are 2,3".


3. Knob pattern

You need to check your tires and try to figure out good knobs for screws.
Wider the knob, more support it gives and wider screws you can use on it.
Check direction of rotation if you want to take that in to account.

1811361

1811361

Gaddaloddis have very sturdy side knobs and quite small center knobs.


Choosing screws:

1. Lenght

First you need to know knob's height, where you are going to insert screws.
Drill through knob and check how deep it goes, add to that 3mm (0.11") to 5mm (0.2")
you are good to go.

Keep in mind that all screws don't have to be same lenght or width. Side
knobs on tires are almost allways longer than ones in the middle, so pick
the one that suits best for your purpose.

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1811354

I got 13mm (0.51") for center knobs and 15mm (0.59") for side knobs.


2. Width

If your tires have wide knobs you can use wider screws. Don't pick too thick
screws, if there is not enought rubber around screws, they can shred their
way out from tire. I recommend 2,5mm (0,098") and 4mm (0.157").

I got 3mm (0.11") for center knobs and 4mm (0.157") for side knobs


3. Type of screw

This isn't so important, it's more like personal preference. Someone maybe
wanna use Phillips screw with self-drilling tip, but I like to use Torx screws
with normal tip and pan head. Pan heads shouldn't have so many sharp edges
which may help you to avoid punctures.

1811355

1811355

I got Torx screws with normal tip and pan head


4. How many?

Knob pattern on tires pretty much shows, how many screws it can hold. If tires
are gonna be used on DH/FR, I recommend 120-200 screws/tire.

Gazzaloddis seems like they would be good with 160 screws/tire. 80 screws to
center knobs and 80 to side knobs.



Back to article.


3 Comments

  • + 1
 This helps me so much, thanks!!
  • + 0
 exxcellent. thank you for doing this
  • + 0
 Thanks!

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