18x8.5 255
vs
18.95 275

noticeable difference? im trying to justify spending $2000 on the nismo rims

 

Noticible in what way?
Handling? Maybe.
Looks? A little.
Cost? Yes.

 

I say there is a difference of 20mm!

 

 

difference =20mm

 

Hard to say anyway, one brands 275 is as wide as anothers 255.

Chris

 

Ask your g/f want difference an inch will do... aha!

 

Okay, on a more serious note...

Aesthetics aside, the handling consideration must include both front and rear tire choice. I'm assuming you're thinking of the rear wheels in your question?

What front tires are you planning to mount? Most here are trying to reduce the Z's under steer characteristics. Unless you're intending to mount 255 tires in the front, 275 might be a bit on the wide side.

Tire availability will play a larger role than you might think, even more so if you're trying to keep the front to rear stagger.

 

1010 Tires has a calculator that can tell you some specs.

 

I was thinking the same, but went to a different install:

I kept my 8"/18" stock wheels (2003 Performance model) and mounted Goodyear Eagle F1 GS-D3 (245/40-18 fronts and 245/45-18 rears). I really like this setup:

1) 245's front and rear give you nearly neutral handling. You notice the difference, especially when entering a turn ("hard") and going-out while applying power.

2) You get great handling for much less cost than an "advanced" staggered setup (i.e., 275 rears and whatever on the fronts) with wider (and maybe taller) wheels.

If you prefer more "show" than "go,", you will mount wider tires and taller wheels.

--Spike

 

Spike,

I do have to add a bit of caution with going with your setup or mine for that matter (I have 275/35 F~275/40 R on 18s).

If a tire company follows the tire spec to the letter, a 245/40 will technically have a wider tread than a 245/45 mounted on the same wheel. Only some tire companies follow it to the letter though, others pick a tread size and then label it accordingly.

My last set of tires where Kuhmos 275/35 and 275/40 and the tread width was identical, like they made one 275 tread and applied it to various sizes.
My current set of Michelin Sport Pilots of the same sizes, the 275/35 F is slightly wider than the 275/40 R by almost a half inch.

Chris

 

Chris,

You are correct. A 245(or whatever) width designation doesn't necessarily mean the tire has a tread width of 245mm. For example, the Goodyear Eagle F1 GS-D3 I am running has a 8.2" tread width on the 245/40-18 tire and a 8.5" tread width on the 245/45-18 tire. Notice that the 245/40 is slightly more narrow than the 245/45 (a fairly insignificant difference). In other brand tires, this could be the opposite (the 245/40-18 is sometimes slightly wider than the 245/45-18 tires). But, the difference is so small that it has little effect upon handling or performance.

The tire industry has set 50 psi as the standard for measurements (section width and aspect ratio). Of course these measurements change when you inflate your Z's tires to 35 psi (as is Nissan's recommendation).

--Spike

 

 

One is a great front tire and the other works great for the rear.

 

the tire numbers do not indicate tread. first number is tire at widest point. tread width is at manufacturer's option.

 

I'm not sure that's really accurate. The widths for a 275 should be fairly consistent across the board. The reason same size, different brand tires fit differently has more to do with the sidewall. (i.e. KDW2 is much bigger than T1R)

 

In case I was not clear. The tire numbers do not indicate tread width. First number is tire at widest point (inside). second number is section height as a percent of width therefor a 275/40 is 275mm wide and the section height is 40% of 275 or 110mm. Tread width is at manufacturer's option.

 

Exactly. You are correct (and explain this well). That was also the point I was trying to explain (and maybe poorly):

The metric tire sizing system represents a tire size as:

[section width (mm)] / [aspect ratio] - [rim diameter (inches)]

For example: a tire size 225/45-18 is 225mm wide, has an aspect ratio of 45 and fits an 18" rim (wheel).

The aspect ratio (the second number) is not a measurement. The aspect ratio represents the tire's sidewall height as a percentage of the tires width (section height divided by section width). In the example above, the sidewall height is 101mm (101/225=45).

The aspect ratio is important since that (along with the wheel size) determines the overall diameter of the tire allowing you to match your stock overall tire height (diameter). For example, a 225/45-18 tire's sidewall height is 101mm, and a 245/40-18 tire's sidewall height is 98mm. So, both tires have nearly the same overall diameter.

Tread width is a different measurement that will be close to (but smaller than) the section width. The only way you can know the tread width is reading the manufacturer's specification sheet for an individual tire (model and size). For example; within the Goodyear Eagle F1 GS-D3 line, the 245/40-18 and the 245/45-18 sizes have identical section widths, but different tread widths.

Hoping I have not just added to the confusion,

--Spike

 

For the reasons in the above post, Falken FK-452's in 275 actually have less tread width than most brands in 255