evilsaint

Bought these - http://www.finishlinewheels.com/spec...5%29+Gunmetal/

Already checked with the sales guy and he said they'd fit, so I'm not worried about that. And as per getting the proper length lug bolts for them, I think I'm covered (suggestions there wouldn't hurt, though). Bone stock suspension, 125k miles.

Now the question - tires! Is there any reason to not just go 245/40 all around like I have been with my current OEM 17's? Or should I go with something more like the 225s in front and 255s in back like most members here seem to? The price difference is pretty much negligible, and I haven't had any handling/wear/rub issues with 245s all around on 17's.

AMG3.2

If you bought a 8.5 all around, then there is no point to buy different size tires. I have the tire sizes you were talking about. My Brabus wheels are 8.5 in the front, and 9.5 in the rear. Respectively, I run a 225 and 255. I am thinking about upgrading to maybe 235 and 265 next time, but the overall diameter does not seem to match up to what I now.

So to answer your question, you'd have to look up the overall rolling diameter and see what matches up with an 8.5 inch wheel and 245.

I'll check for you in a little when I find the tire calculator online.

Edit, to run 245's on 18's you should get some 245/35/18. The radius (12.4) is exactly the same on both specs so you should be good to go. If you bought 245/40/18's like you had on your 17's you would have too big of a sidewall.

evilsaint

For the sets of rims that come as 8.5's in front/9.5's in back (I'm guessing that's what they refer to as staggered?), is there any point past more rubber in back for better traction?

*edit* http://www.miata.net/garage/tirecalc.html

I think I understand now. For as long as I've been working on cars, I don't think I've ever not just winged it when picking tire sizes >_>

Keeping 245/40s on the drive wheels would make a 4% difference, give or take; 2.5mph at 60mph. Might it affect the speedometer, or does the car calculate all that in the tranny? 245/35/18s would match up to the same revs/mile, but those are going to be a ***** to find down the road, pun fully intended.

AMG Sleeper

Most guys on here with a non-staggered setup typically elect to go with same size all around, for the reasons mentioned above. I think 245/35 is the way to go.

Have you picked out a brand of tire yet? Might I suggest the Hankook Ventus Evo V12... great tire, long tread life, good weather performance, and still handles as well as my former Toyo Proxes T1Rs for a way better value. If I ever get an all-wheel drive car (or even set up like yours), these are the tires I'd put all the way around

LuisC55AMG

Let's say that I have 2 pairs of wheels, a pair of 18*8.5 (front) and a 18*9.5 (rear). Is it possible to attach the 225/40 R18 and 245/35 R18 (respectively) into those?

I have a new set of tires on OEM wheels, I don't want to replace those, yet...

evilsaint

Most people seem to go with 225/40 on 18/8.5 front and 255/35 on 18/9.5 rear, so you should be fine. Don't quote me on it, though =)

evilsaint

I was actually looking at those on the advice of somebody else here on the forums, but I found a four-pair of Conti ExtremeContact DWSs through a friend for $360 shipped, so I couldn't pass it up. 235/35/18s but hey? For that price, I'll give up a little rubber

AMG3.2

That is such a good deal! I want to get the Extreme Contact DW next. They are a super good tire, and are a whopping 2lbs lighter each than my current Dunlop DZ101's. 8 pounds of unsprung weight is a lot lol

evilsaint

Check out Tirerack, that's where he said he got 'em. Search for that size specifically, or just weird sizes in general, and look for the prices with "Special" next to them. He didn't say if they were limited availability or anything, so maybe you can still get lucky

AMG Sleeper

That's super cheap! Wonder how much they cost in 19s? lol