Could   be 5/16" which is very close to M8 (7.9375mm vs. 8mm). Thread might be UNF 24 (24 threads per inch) or British Cycle Std. at 26 threads per inch. There are even some that are metric in terms of diameter but use BSC for thread spacing! If it's 5/16" at 26 threads per inch then an M8-1.00 nut may fit since 25.4 tpi is very close to 26 tpi and 7.9mm diameter is very close to 8mm.

what size can be the nuts holding the front wheel?
I have a short description for each of my equations. I want to have them flushleft (similar to the equation numbers which are flushright). How can I do that?

Here is a MWE:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
\text{this is my first equation: } z = x
\end{equation}
\begin{equation}
\text{this is my second equation: } z = x+y
\end{equation}
\end{document}


And my desired output is like this:

