Missing sizes in impact socket set

[ECR]

15mm and 16mm are not included in my impact socket set and a quick look on ebay shows them missing from other sets. They exist of course and I can buy them individualy.

Anyone know the reason, just curious .......

[CharlesElliott]

15mm - because it doesn't map closely to an imperial size.

[Jonathan Kay]

I checked 4 sets on Amazon UK, and 3 had both. I doubt if there is a deep reason.

Jonathan

[Titanium7]

 Unlucky numbers in China? 

[Roger Ford]

European cars use 8, 10, 13, 17, 19

Japanese cars (or at least bikes, assume cars are the same) use 8, 10, 12, 14, 17

So 9, 11, 15, 16 and 18 aren't generally used.

[ECR]

That makes some sense Roger, thanks

Would somebody tell the people at Lotus who attach the CAT please

 

[CharlesElliott]

My Porsche and Audi have both used 15....but it is not common. I do have a 15mm spanner for that reason though!

[LesG]

As someone who sells tools for a living, I can tell you that 15, 16, and 18mm are used a lot on European vehicles. 

ECR; the reason your set is 'missing' those sizes will be down purely to cost, and specifically to appear better value/ more competitively priced than other makes for similar money. The moral of the story is to check what is included in the set before you commit to click the buy button........

[aerobod - near CYYC]

BMW definitely moved to 16 & 18mm over 17 & 19mm sockets about 10 years ago, they now seem to be favouring spline sockets and bits instead of hex or torx ones for many bolts.