Wider Tire on Stock Rims? (2006 Infiniti M45 Sport)

[The Archangel]

Howdy. I have a 2006 M45 Sport and it's that time for me to replace some of my tires. I am looking at the GoodYear GS-D3, but in 255 40 19. The stock are 245 40 19. I know it will physically fit on the rim, but just wanted to make sure that the difference in size from OEM would not affect the traction control reading(s) and/or cause me any problems that I may not forsee at this moment.

Here is a link to the tire http://www.tirerack.com/tires/...ing=Y

Thanks in advance for any help on this matter.

[szh]

Howdy. I have a 2006 M45 Sport

Welcome to NICO!

I am looking at the GoodYear GS-D3

That is an excellent, superior tire, by the way. I have been using and recommending it for a while. I just bought four of them for my wife's Acura literally this afternoon! Albeit in a completely different size (205/55-16 for her 1997 Acura CL).

but in 255 40 19. The stock are 245 40 19. I know it will physically fit on the rim, but just wanted to make sure that the difference in size from OEM would not affect the traction control reading(s) and/or cause me any problems that I may not forsee at this moment.

In terms of any problems, I would not expect any major issue as long as you use the same size on all four rims. So that there is no difference in rolling diameter from front to back. And, I think (but not entirely certain) that this 10mm increase is not going to cause the tire to touch anything. Plus, the speedo error is generally minor enough not to matter either!

But, one thing I would point out though. This is a very subtle effect though, so you can feel free to ignore it!

The stock 19 inch wheel is 8.5" wide. This is the minimum width that should be used for the 255/40-19 tire (range is 8.5" to 10.0"), and the measured specs are shown at a 9.0" wheel width. OTOH, for the 245/40-19, the wheel width range is 8.0" to 9.5" and the measured specs are shown at a wheel width of 8.5" - which is exactly what the stock rim is!

With the wider tire, the actual stock 8.5" width means that the inside of the tire is subtlely curved inward ... lifting the outer edge of the wheel just a bit more than with a 9.0" wheel width (the tire sits differently on the rim). This means that the actual tread and section widths will be slightly less than what is shown at Tire rack - by a small amount.

You cannot compensate for this by lowering the tire pressure, since that could make the load index of the tire too low for the weight of the car. That is dangerous!

The net result is that the performance "gain" in going to a wider tire is not as much as you might think ... in certain cases, the narrower tire might indeed perform better because it places a "better" footprint on the ground at normal pressures.

So, I would hazard a guess that these two sizes tires will perform very similarly on your car. Plus, the visual difference between a 245 tire and a 255 tire is mostly not perceptible, so purchasing for the "look" is not relevant anyway.

Not an intuitive result, huhn?

(By the way, the only reason I would consider doing this change, though, is that the 255/40-19 tire is $30 cheaper than the 245/40-19 tire at Tire Rack!)

The overall point is that when people want to change the width of the tires they use for their car, they also need to think about what wheels they should put it on!

Z

P.S. BTW, the reason I went from a 235/45-18 stock tire size to a 245/45-18 tire size on my 2003 M45, was because of the much larger availability of tire brands and models (and also, lower prices) in the 245/45-18 size! I do not think I gained in performance or looks in any meaningful way at all.

I am currently running the 245/45-18 100W Goodyear Eagle F1 GS-D3 on my car and love it! It is one of the best tires I have ever used in 30 years of driving - second only to the now-discontinued Firestone Firehawk SZ50-EP for my personal criterion for tire selection: wet weather braking and handling.

[The Archangel]

szhosain,

Thank you for your response. You are correct, the main reason that I went with the 255's was the $30 savings per tire over the 245's (also wanted a better tire than the stock Potenzas). I called to ask TR why this was and they said that it was a manufacturing stocking issue (they make more of those 19" tires in 255's).

I just had them installed on my car yesterday and they feel terrific. I feel a lot more confident on the freeway. They hold the road much better. The best way to describe the Potenzas is that they feel "wobbly." Almost how a car feels on the freeway under heavy side winds. The GS-D3's feels firm, solid and just carves the road (no wobbly feeling).

This is not my first experience with these GS-D3's. I had an 01 Cobra Mustang with 315's (GS-D3) on the back.

Miss that car...

[lswaidz]

That second picture is just about perfect for a Cobra... what a great looking a**.