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Discussion Starter · #1 ·
I have these:



And am having the hardest time selecting the best tire size! They are 18x7.5s and I've been considering 225/40/18 kumhos but idk..

And obviously I don't want them to run nor get insanely low gas mileage

Answer?
 

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225/40 is the size i run on 7.5" wide medusas, and i can't wait for warm weather so I can put them back on my car... your call though. I did a lot of research and ended up choosing 225/40/18 bridgestone potenza pole position RE050A. I loved them last summer and they're crying in my shed right now...
 

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Discussion Starter · #3 ·
Re: (mattdoc)

Quote, originally posted by mattdoc »
225/40 is the size i run on 7.5" wide medusas, and i can't wait for warm weather so I can put them back on my car... your call though. I did a lot of research and ended up choosing 225/40/18 bridgestone potenza pole position RE050A. I loved them last summer and they're crying in my shed right now...

Alright, so no rubbing? and what kinda of mpg are you getting?
 

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I had a nice reply with lots of help but when I tried to post it, the board basically told me to stick it up my you know what.

What you want to do, is keep the overall diameter of your tires the same.

Search google for a "tire size plus one calculator", and you should find something.

A basic breakdown is this: if you are running a 225/40/18, 225 is the width of the tire at the widest point. 40 is the ratio of sidewall to width, so in this case, 40% of 225. So you have 18" tire, with a 90mm sidewall. Now figure out what the overall diameter is, and then do the same for what you are running now.

Or, you can just go here: http://www.1010tires.com/tiresizecalculator.asp


That better work this time.
 

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My mpg might not be a good comparison because I have a T5, but I can easily get 30 on the highway if I keep it at 65... So I usually get 21 mpg overall.

If you're coming from the stock 17" 50 profile tires, a 18 with 40 is a good match for the diameter.

I have never noticed any rubbing, and my car is not lowered. I'm not afraid of rubbing if I lower it, though, due to others' experiences.
 

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Re: (Kallvin22)

on an 18 x 7.5 you really only have 2 choices. The 215 45 18 (what Volvo uses and this is what I have for my winter Medusas) or the 225 40 18,

ok, I've heard of at least one person put 235 40 18s on an 18 x 7.5 =too wide IMO . I've had 235s on both an 18 x 8 and an 18 x 8.5 , some 235s rub , some don't . so to be safe stick with 215 45 or 225 40

you'll find more 225 40 18s than 215 45 18s , I'm going to guess that the 215s yield slightly better mileage, (could be that I drive somewhat slower in the winter) but even so my best is 335 miles before the low fuel light came on...( my worst 230 miles)
 

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Re: Yet another wheel/tire question (Kallvin22)

I'm running 225/40R18 General Exclaim UHP's on my Medusas and they fit great. Also, as was mentioned the difference in diameter between stock is negligible so there's no speedo adjustment necessary.

If fuel economy between different tire models is a point of contention you shouldn't be considering getting performance tires period. Sell your 18's, your shirts, pants, and your underwear and go with 16's. You'll never recover the cost difference between these tires and 18's with any savings in mpg.
 
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