To read the original full thread and post questions/comments on this topic, please go to Spare Nuts and Bolts
The thumbnails below are from the Repair Manual and also listed in the Service Specifications. One page lists several classes of bolts, with size, pitch, and torque. Another lists how to determine bolt strength. The last page lists how to determine strength of nut.
This may not capture all bolt and nut sizes. For instance the lower arm bolts are purchased as a bolt set, and do not call out the size.
One last thing, the bolt size to wrench size for the head for Japanese Industrial Standard is as follows:
4 mm bolt - 7 mm wrench
5 mm bolt - 8 mm wrench
6 mm bolt - 10 mm wrench
8 mm bolt - 12 mm wrench
10 mm bolt - 14 mm wrench
12 mm bolt - 17 mm wrench
14 mm bolt - 19 mm wrench
16 mm bolt - 22 mm wrench
There are four primary considerations for spare bolts and nuts: (1) diameter, (2) pitch, (3) class (strength rating), and length (bolts only). Toyota was nice and standardized on only one pitch for each thread diameter, as follows:
6 mm diameter - 1 mm pitch (iso course) - requires 10 mm wrench to fit head / nut
8 mm diameter - 1.25 mm pitch (iso course) - requires 12 mm wrench to fit head / nut
10 mm diameter - 1.25 mm pitch (iso fine) - requires 14 mm wrench to fit head / nut
12 mm diameter - 1.25 mm pitch (iso other) - requires 17 mm wrench to fit head / nut
14 mm diameter - 1.5 mm pitch (iso fine) - requires 19 mm wrench to fit head / nut
16 mm diameter - 1.5 mm pitch (iso fine) - requires 22 mm wrench to fit head / nut
The class (strength ratings) range from 4T to 11T (Toyota's rating system). However, the simplest way around this is to carrying only SAE Grade 8 (sometimes stamped 10.9) spares. This is the typically the highest strength for a non-stainless bolt or nut and eliminates the risk of not having the strength of bolt/nut required when replacing with a spare. If possible look for a nearby bolt in the same service, note its class stamp, and torque according to the companion bolt (not the torque for the highest class
). Ideally went you get home, replace the bolt/nut with the correct class.
Another thing to think about is Toyota uses both hexagon head bolts and hexagon flange bolts that have different torque specfications. I would only carry spare hexagon head bolts and flat washers (to simulate a flange bolt in a pinch).
So now we come to bolt length. Toyota uses bolts of various lengths (same diameter / pitch) depending on the application. I carry 6 mm bolts about 3/4 inch long, 8 mm bolts about 1 inch long, 10 mm bolts about 1-1/4 inch long, 12 mm bolts about 1-1/2 inch long. There are 6 each nuts, washers and bolts of the above size in my traveling tool box, except for the 12 mm size which I only have 4 each.