A valid digital signature gives a recipient reason to believe that the message was created by a known sender (authentication), that the sender cannot deny having sent the message (non-repudiation), and that the message was not altered in transit (integrity).
Load index is an assigned number that corresponds with the load-carrying capacity of a tire. Most passenger car tire load indexes range from 75 to 100, but a few carry more. You'll also find the maximum load elsewhere on the tire sidewall, both in lbs and kg.
The maximum load number, (1653 LBS) is the load carrying capacity of the tire when it is inflated to the maximum inflation pressure. Similar to inflation pressure, this is not the recommended load carrying capacity for the vehicle it is installed on.