Options for new tires or rear rim+tire

Hello, come February-ish I will have my 2012 GT Hellion twin turbo'd(around 600rwhp to the tires) and I have been going back and forth with just getting new tires for my 18x10 rims or trying to snag new rims also. Currently I had decided on the nt555r on 305/40/18, the car is my daily in the good months and I drive 70 mile round trip for school most days of the week so the nt555r seems like best for me. I know the tire would be better suited on a bit bigger of a rim but if i stay 18in I will stay with these rims. My other ideas have been to drop rim sizes and try for a wider rim but going to 17's and the nt555rs throws the speedo off by 5 and is 315s, or I am willing to drop to a 15in rim but for the nitto is a 325 which seems too big to me. So I am just looking for idea/suggestions aside from the shop doing the work(he is fine with me staying on 18x10 with the nt555 305 but I havent asked him about changing from those as I feel I need to know my best options before presenting to him). Thanks!

IMO, pick the tire and then just adjust the tune for the revs/mile for the speedo, you must have a handheld for the custom tune you have, it's a 5 min adjustment to recal the speedo


as for the tire, the 555r is the least sticky of the DRs, yes for a DD it's probably a solid choice for tread life.

the 305/40 is fine for a 10" rim, would it be a bit better on a 11" rim, sure, but will work fine on the 10" rim

if you don't track the car, I'd not go to the 15", stick with the 18s.

one other choice, would be a M&H 325/40/18 - they will not last as long, but they hook much better, they fit fine on a 10" rim, I've been using them on mine for about 8 years. See \/

I have been previously going to the strip 2 maybe 3 times a year only, I hope for more once the car is done but will probably avoid the 15s then unless I get more cash for dedicated drag set. I wish my drive wasnt as long so I could go to a stickier tire but that will have to wait for now. I appreciate your response and unless I can get some great deal for switching from the 18's I will just stay.

Adjust trpm with the handheld tuner.