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.
Tires are given a maximum load rating based on the tire's size, construction and inflation pressure. P-metric sized tires--tires with sizes starting with a P such as P235/75R15--are given a load range rating of either SL or XL. SL stands for Standard Load and XL indicates extra load. An SL-rated tire has its maximum load capacity at an inflation pressure of 35 psi. XL tires can carry a heavier load when inflated to 41 psi.