An additional advantage is that a full set can be carried in the boot just in case of snow. I realise that this won't be possible for Ed38 people whose boots are full of subs, amps, floor tiles & spare trainers for impromptu photo shoots
Just make sure you have a spare in the car, i wager there'll be no end of grief if you have 4 space savers on, get a flat and havent got a spare I dont see why countersunnk screws wouldnt be ok, if placed correctly they would have MORE grip than rounded ones. Perhaps it's be a bit more risky in terms of ripping a screw out of the tyre (i can see how it'd do it with countersunk and but not rounded, but not really describe it easily in a consice manner ) But they would offer better grip. maybe. Still the point is risking being caught on studded tyres if they are indeed banned for road damage reasons. You might stick out a bit rolling on 4 pram wheels, perhaps get some hubcaps to cover it a little? Also, pics if you do!
They won't puncture due to them being filled with expanding foam filler (see earlier post) Obviously countersunk screws are unsuitable by their very nature, they are designed to be fitted flush with the surface hence they would offer no traction
Would it be worth completing the product range with a roof rack supplier? Possibly some designer straps also, in dayglo colours? Just a thought.
I don't know - it's a public service, giving pre-pubescent teenagers a prospect of not driving up the nearest lamp-post. Make sure you add VAST to the sale price
i did this once, by the time i'd screwed 80-odd screws into a spare set of front tyres the snow had all but melted. went for a spin and they both popped after a mile or so, i had to drive back with the sound of self tappers grinding my rims from the inside out. they did grip pretty well though!
Thanks to the support from Phat Ass, I decided to work up this CAD image... I think this closes any discussion about the use of countersunk screws.
They are designed to be flush, but this is hardly their design purpose is it The idea would be that you dont sink the screw heads all the way into the tread. It should in theory damage the road less then having a large smooth round head on the top and just have a small edge on top of the tyre tread. I still say they'd grip better than round heads and be much easier to put in with a drill given slot heads tendancy to slip out from the bit (i cant say that i've seen posi-drive round heads from memory). Kudos on the expanded foam however.
What about braking? Angling the screw in that manner may enhance traction under acceleration but would not be as effective for braking or cornering, whereas dome headed would offer the same level of grip for all forces imposed on the tyre.
Posted before i saw the image. The angle of attack for the screw would have to be perpendicular to the edge of the tyre and not slanted. If it was slanted then when/if you get stuck and need reverse you'd have very little traction by comparison to when in forward gears. The edge of the countersunk screw would provide much greater traction than that of a round head screw which was driven in level with the tread and have less of a shearing effect than putting a round headed screw further from the edge. Theoretically.
With access to policey-type stuff, couldn't you modify some 'stingers' to simply wrap around each tyre? Would probably need no fixing once you'd rolled a turn or two on them.
It's amazing how quickly people start nitpicking when faced with an intellect clearly superior to their own, if you lot are all so clever why didn't you think of it in the first place?
Duh! Stingers are designed to allow the spikes to pull out of the frame, beisdes which the spikes are too long & would foul the arches of any lowered cars. Leave the thinking to me please guys
