Just curious, I have Kumho Exsta's 225 40R-18. I have 18's Mille Miglia rims. Wondering if I could go with more of a tire if you know what I mean. This tire was recommended to me when I had the rims put on from America's Tire Store. The ride is just so harsh. I know some of this is due to the drop, but these tires have got to go.

i have 235/40/ZR18 Toyo Proxes FZ4 on my Mille Miglia Actions.

for summer i have toyo, fz4 235/40/18, going to to get 245 when these are through,
as for as big as you can go, a while back in the tire forum, I think there was one guy running 255/50/18 on a 5th gen w no problems

Really? What was the width on the 18's? If I would've known that I could've run a 50 profile, I never would've sold my 18s for 17s

Depending on the width, offset of your wheels, and amount of drop, you should easily be able to go with 235/45-18 or stretch it to 245/40-18 (need an 8" wide wheel). Both of these are almost exactly the same diameter as the stock tire size so there will be no spedo error. Your 225/40-18 are over a 1/2 smaller in diameter than stock so your speedo is prob. off a couple mph +.

I thought I could go with another tire size. I hate these. Would there be much of a difference in ride quality if I went up to a different size?

There's a couple things that contribute to ride quality, 1)Is the style of tire, summer, all season etc. since all the tires in these sizes are built with the same theory in mind, performance, we can call it even. 2)Is the height of the sidewall... the height of the sidewall on your existing 225/40s is 3.55 inches, on the 235/45-18s it is 4.16 inches, and on the 245/40-18s it is 3.85. Both of these have a fatter sidewall which will soften the ride a little but lets face it, they're performance tires in a performance tire size. If you want ride quality go back to the stock size tire. The sidewall on the stock size of 225/50 is 4.43 inches, almost an inch more than what you have now.

I'm running 245x40x18 on 8 inch wide rims. Ride quality is good.

I have 235/40/R18 tires on mine but will be moving up to 245/40/R18 for this summer.

18x8 35mm offset with 245/40ZR18 Nitto NT555's

You don't need 8" wide wheels to fit 245s. I'm running 245s w/ my 7.5" wide wheels w/out any problem.

235/40-18. My ride is harsh but I'm on Eibach's with stock shocks.

245-40-18, i'm running on mille miglas evo5s, progress springs, illumina shocks, no problems whatsoever

what does the first number on the tire size mean... and the second? like 245-40?(im tire alliterate)

245 is the width (in millimeters)
40 is the ratio (i.e. 40% of the width, i.e. 245 x .40 = sidewall height)

by the way, in the context you're using it, it's "illiterate". "alliterate" is a verb that has a different meaning. Sorry, couldn't stand the irony of that!