hey everybody,
i'm sure this has been debated before but i cant seem to find any of the threads, plus i havent been on on the website in a while. anyways, i have a 2004 G35 sedan with sports package. i've had it for a little over a year with about 17,000 miles and my tires are close to gone. i do drive agressively so i'm not surprised. currently i have the stock goodyear gs-d which are w rated tires. however, i reallly want z rated tires. i cannot find a tire that is z rated in 215 55zr17. since i am set on z rated, should i increase width to a 225 50 perhaps, or decrease aspect ratio only to a 215 50 or 45. either way i dont want the tire to look funny on the rim. the head mechanic at infiniti said that a 225 could roll over on a 7 in wide rim. and a smaller aspect ration would make it look to thin and awkward. what is my best compromise or solution. problem is, i dont want to buy 4 tires, put them on, and i dont like the way the look or perform. any help appreciated. sorry it took so long
Brett

 

I replaced my OEMs with 225/55/17 Falkens and I really liked the look. They were slightly taller than stock but in the 1% range. They handled well and were comfortable.

He should change his title to "head putz"... sometimes I wonder if people actually put any thought into what they're about to say.

I currently have 235/50/17 Kumhos and although the rolling circumference is almost identical to stock, I think they look a little wide for the rim. I prefered the look of the 225/55s.

With that said however, tires vary greatly depending on manufacturer. The same size tire from different manufacturers can be of different heights and widths... there's a lot of variance.

When my Kumhos wear out, I'm going back to 225/55/17s (i.e. if I don't upgrade to 18s).

 

When you said you think the 235/50/17 is too wide for the rim, is that visually? Like the tires are sticking out more than the rim if you look at it from the side of the rim?

I am thinking about replacing my crappy Turanza 215's with Avon 235/50/17 A/S.

Do you have any pics of Kumhos on your car? I don't like the Turanza's. Poor handling and 215's are kinda skinny.

 

235/50/17 is a beautfiful fit.

 

...and I'll make my usual Eagle F1-GSD3 recommendation. I'd be doing the world a disservice if I didn't sing the praises of these tires at every opportunity. I can't wait for my wife's tires to need replacing, since it means I can buy another set of these for her car too

They're absolutely rock solid on every aspect and they'll end up outlasting my original Turanza's. At 13,000 miles they're right at 50% worn.

 

Check the Tirerack. There are Z-rated 215/55R17 out there. I plan on getting all season Z-rated Avon M550s ($110) to replace my super crappy EL42s.

 

Why all the fuss over Z rated? Wouldn't V rated be sufficient? You can probably get a better tire for the same money and as a bonus get a slightly softer ride. Probably more choice too. V is rated up to 149 MPH!

 

sorry those avons on tire rack are w rated not z rated. i dont think 215 55 17 z rated tires exist. basically, while this might not be for everyone one, i want a summer tire with the highest grip. quiet ride and comfort are not that important to me. what about going with a 225 50 17, anyone have this. 235 widths scare me about being too wide on a 7 in rim, even though some do have it. any more ideas would be helpful, thanks!

 

Highest grip, summer handling, performance tires. Again... Eagle F1-GSD3s. Hell they're rated higher than Z! They're rated Y which is 186mph.

235 too wide? No way. I have 245 and I'm not even seeing uneven wear (which was the worst thing that might happen according to guys at tirerack and discount tire.)

Nothing but happy times. They bulge a little though so next time I'm going with 235. (235's were backordered when I needed tires) 235's will provide you with a nice square sidewall. They literally fit perfectly, and the OD is as close as you can get to the stock size. You have a billion more tire choices too at this size. I don't know why they didn't use this size from the factory. - Oh that's right, they saved $1 per tire.

235/50/17. Embrace, Shop, Buy.

I went ahead and took the liberty of finding the page where you can click "add to cart"

http://www.tirerack.com/tires/tires....e1=yes&place=0

 

um... arent all w rated tires z rated also?

w is just to specify that the tires can go up to what speeds. that's what i take it to be. am i wrong?

 

Ummm...W-rated is good to 168mph (ie better than Z-rated).

 

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.


- Tire Rack

 

tire rack has a section where it states this "We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 ÷ 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall." basically by using this calculation, i would have to agree that 235 50, would be the best fit. if you do the above calculations the #'s are almost identical to 215 55, very interesting. however do any any problems with the tires "rolling over," because on goodyear's website although they are approved for a 7 in wide rim, it says a 7.5 in wide rim is recommended.
also, this is what i believe and tire rack does also. z rated is 149+, meaning in excess of 149, say like 200. however w rated is a maximum of 168 and y is 186, so while it might appear that w and y rated are better, z is because it is in excess of 149, z rated tires max speeds are not tested but if they were if would be higher than both. i am no tire "specialist", however this is my understanding and if you look at tire rack, it basically says the same.

 

The Tirerack site is very useful and your calculation is basically correct however one companies 215/55R17 could be .3" shorter or .5" narrower than some other companies 215/55R17. What you need to be looking at on the Tirerack site is the spec's page for the particular tire you're interested in. Those are the EXACT specs from the manufactuer. That will tell you everything you need to know about fitment, weight, and diminsions. The Avon M550s are W-rated ultra high performance all season tires. What I really like about them is that the 215/55R17s M550s have a .5" wider contact patch and a .6" overall wider width than my crap 215/55R17 Turanza EL42s. That means the M550s are will handle better and will pull the tire square, ultimately giving the car a better look and making the wheel gaps appear smaller.



Not true. If this was the case 911s, Vipers, Ferraris, and Vettes would have Z-rated tires. They don't. They have W and Y rated rubber. The universally accepted topspeed rating of a Z-rated tire is 154mph.

 

Z is a rating that is kind of obsoleted by Y and W. You'll rarely see a Z tire that doesn't ALSO state Y or W now.

Tires don't roll off of rims. You might see uneven wear with a too-wide tire, (usually more wear in the center) or even tires that rub suspension components or fenders, but they just don't come off of rims. Something that provides a sidewall angle that is greater than designed for that tire will obviously have an effect on sidewall performance and therefore handling, but a tire won't come off the rim because it's too wide. If you're exerting enough force on the tire to make it come off the rim, it's coming off whatever the size of the tire, and you're probably about to die anyways, so it's moot point