I was looking into getting some 18 inchers on my Cl-S. I got sways, H&R OE springs, and Illuminas. Those are my suspension upgrades, how much rougher will my ride quality be with 18 inch rims on 45mm tires. This is my everyday driver, hopefully you guys can give me some input.. Thanks

 

It will be stiffer, but not a ton. As long as you dont get rubberband or cheapo tires it will be ok. The better question is do you plan on running them year-round, and where do you live?

What exact tire size are you looking at, and offset of the wheels is important to make sure u dont rub.

 

I never really got into rims much, but what exactly does the offset mean. I plan on getting the Rotora BBK down the road. I am not sure if this would make the offset have to be different, I just know I do not want to get spacers. I live in PA, and the winters get nasty, but why would I need to take off my rims if they arent gonna be chrome?

 

Because 18's require lower profile tires, which are more prone to pothole damage. Plus, why spend a crapload of money on wheels to ruin them with winter salt? Keep your stock 17's for winter and get some nice 18's for the warm months.

Salt will eat away at the clear coat on silver wheels also, so its not just chrome that it affects.

Basically all you have to know is that you want 18x7, 18x7.5, or 18x8. You want the offset to be between +45 to +55. You should go with 235/40/18 (better fit & size, but more possibility of rubbing) or 225/40/18 (lower profile so less chance of rubbing, but firmer ride and speedo will be off slightly).

 

There is no way I am going to go with a 40 tire, thats just asking to have bent rims year round. I travel, so even if I lived in an area with no potholes, I still have the chance of hitting one of those suprise monsters in another city. I figured 225 45 18 would be ideal for 18X7.5 rims, Why would you want to go with 40, the car probably handles good enough with 45's, and as for rubbage, my stock rims still dont have any curb scratches on them.

 

225/45/18 is about 4 tenths of an inch taller than stock, so it will make the speedo read
a little slow (but will also cause you to accrew less miles). If you can live wiith a slightly taller looking tire I say go for it, but 235/40's arent THAT much smaller sidewall'd than stock, and are 100% identical to oem tire overall diameter.

 

But with the 40 tires, isnt it going to be a harsher ride than with 45's. Overall, which is the safest, most reliable(least likelyhood of being bent), and best riding size to get. Also, what offset would I need ot look for so i dont need spacers when i get the Rotora BBK .