Newby to the Jimny

hi,

I am both new to this forum and the jimny. I bought a 2002 model, and loving it despite the spartan nature of the vehicle. It was a bit of a impulse buy as i was looking to get into 4wd, never driven or owned one but liked the car...

Since owning the beast i have put a 2 inch lift kit on it. But other than basic maintenance that is it. I have been reading as much as i can and this is the crucks of the post, as i need some help and clarification. 

1) i have a m13a engine, am i right that this has a timing chain as opposed to a belt?

2) i want to upgrade the tyres and was thinking it would be safe to go to 215/75/15rs. However the more i read, the more it talks about power loss on a stock engine and the sluggishness of just this upgrade... which has me a little concerned as i will drive a bit of highway and off road mostly beach at least 6 times a year and at this time dont want to upgrade the engine (but i could be convinced). Btw i currently putter along at 90km/h on the highways on the stock 205/75/15r as this seems comfortable at 3500rpm for the lil beast. 

Any help would be appreciated