Brad4rdHay

I was thinking: look at the specs for many high horsepower sports cars (ferrari, lambo, porsche, GT-40, ect), they all have very wide rear tires, but most have quite skinny fronts, alot have basic 225 fronts.

Is this because a skinnier front tire will be less succeptableto tramlining and have sharper turn in response? Im thinking that 245s up front in the Z could be overkill.

BUT, would having 275s in the rear, and 225s up front increase front push any?

rodH

iTrader: (2)

remember, those are Rear and mid-engine cars, which are lighter at the far front of the car and lighter overall.

OP Z

iTrader: (1)

Narrower front tires give better straight line acceleration due to less rolling friction. Look at dragster front tires.

Brad4rdHay

I see what your saying Rod, but the Z comes with 225s stock, when they could've easily gone with 245s all around.

Im just thinking that while the 245s might provide a little extra bite at that last 5% of the limit, the narrower tires will provide beeter tactile feel and feedback the other 95% of the time.

I know I'd have to go to a higher profile for my 19s if I did...225/40/19 (which would put them 4.7% taller than stock...about the same as running 275/30 series tires in the rear instead of 35 series. as many do in Japan...i.e., the latter makes the rears anout 5% shorter than stock, my proposed setup makes the fornts 4.7% taller than stock)

Blue Liquid

I beileve a 225 front and a 275 rear will have a significant wheel diameter change, enough to throw off your speedometer (and ABS, VDC, TC) by a significant margin. Keep in mind, this also affects mileage. Your odomoeter could read more of less mileage than is actually on the car. I did the math on my last car, and after ~20K miles, I had an additional 427 miles on the odometer which were not actually driven. Call Tire rack, they did the math for you and tell you what is recommended to keep the wheel diameter in spec with stock, which is how the instruments and electronics are calibrated.

Brad4rdHay

Width has nothing to do with spedo errors...the height of the wheel/tire does. If I went from a 245 to a 225 then I'd raise the aspect ratio accordingly, which, like I said, will get me withing 4.7% of the stock height.

Im worring about performance benefits/disadvantages with skinier fronts.

GaryK

Running a 225/275 combo is going to make your car push like crazy. The reason Nissan put a slightly narrower tire on the front is to make the car understeer. Most manufacturers do this (set it up for understeer) because its safer for the average driver. Running an even bigger split than stock is going to make it worse.

Brad4rdHay

Ok, but what about these sports cars that have huge differences between front/rear that DONT push....is this because they designed the suspension setup around this tire combo.

Or did Nissan just use the decide that 245s were adequate to handle the cars power but wet to 225s up front because they were more responsive?

Z33

IMHO, 245 and 275 seem to work well together.

Today I had 4 new 18" Michelin Pilot Sport A/S installed: 245x40 on 8.5" and 275x40 on 9.5" Volk Racing LE-37T in gunmetal. The stock RE040s had developed an irritating whine, pushed like hell and the rears were prone to spin under most conditions, especially in cooler weather.

The new setup is very well balanced, much more bite on turn in and better grip overall, pretty much as expected. The Michelins are quieter than the Bridgestone's were when new, and work better in the rain (it's rained off and on all evening). The lighter-than-stock Volks offset the larger, heavier Michelins, and the ride is noticably smoother. Much better wear rating, as well; at 400, they should last a while.

The wider tires look great, and at a 30 offset, are further out, not quite to the edge but enough to make a real difference. The gunmetal works well with Silverstone, and the polished lip sets them off nicely, with no bling at all.

About the only downside is the cost (~$3700) and loss of the remote tire-pressure sensors, which, BTW, the onboard computer seems quite content with. I can live with that.

I'll post pics when I get some good weather.