What do the Sidewall Ratings mean?

What do the sidewall ratings mean? For example, I see that Nitto Terra Grapplers come in sidewall ratings of D & E. The price difference on a set I found is $26 per tire (E more expensive). Does this matter for the Tacoma? When would you want the higher rating?

Thanks

 

i think it relates to load rating... dont quote me on it but i think thats what it is... and obviously e would be the best

 

C, D, and E are the ratings you'll find on LT tires. the C is a light load rating but is fine on the Tacos. E is the heaviest load rating and is for the 3/4 and 1 ton diesel guys mainly. you can run the D and E range tires but the sidewall is stiffer so they will most likely give a rougher ride and wont conform as well when aired down 4wheelin. I've heard that the higher load range tires have a harder rubber compound and will last longer on the lighter vehicles too. i think usually it'll go 6-8-10 ply ratings from C-D-E too.

 

Thanks for the info.