not sure if this has been discussed(?)
How would it look/perform with 255/40/18 on 8" wheel?

I could not find pics of this specific size..

 

Pretty perfect actually.

 

winter setup?

 

I'm running a 275 on a 8" wheel. No complaints

 

Really???? Haha im running 275 on 9.5 and i fibd it perfect. I wouldnt put 275 on 8. Way too small of a wheel for the tire size. Just me though

 

Domestic guys do it all the time. I've read people putting up to a 315 on a 8" rim (DR)

 

Depends on the need and depends on the tire construction. On a sports car that is made to handle, 275 on an 8 would be a sloppy mess. If your into that straight line monkey racing stuff or drive a non handling led sled, tires like that are ok

 

DD and autox possibly.
Didnt know everyone would say yes.
This would save me some money from buying new rims.

 

^^^^ This.

I think I mentioned the "old 1.2 rule" the other day.

Tire width should not exceed 120% (hence 1.2) ofwheel width for max performance. You can physically fit a larger tire on the wheel than 1.2x but performance drops off due to sidewall slop and contact patch squirm (or as Terrasmak aptly refers to it, "a sloppy mess".

Again.... 8" wheel x 1.2 = 9.6" tire or 243.84mm (245) is about max width tire one should run on that width wheel.

 

But like everything else, you have a trade off. 245 would be good for handling, but 255 would be better for acceleration. More contact patch is always better right?

Personally, i like the best of both worlds. Thats why i run 275 on 9.5 a 1.15ish sizing so theres that haha

 

very knowledgeable people on this forum!

 

I agree that we have excellent Moderators on my350z.com; They know “their stuff.” MicVelo is really good. He backs-up his statements with science and verifiable statistics.

There is a wealth of information here from many sources: moderators, owners, and vendors.

 

Yes and no, depends on where that 255 is, obviously. Placed on the rear, sure, you get better hook up on launch from standing start (than a 245 by a fraction) due to additional rubber on the ground for traction.

But in the grand scheme of things, acceleration - say, from a roll (real world or on a road course) - doesn't really care that much other than whether or not you can deliver power to the ground. If you're running a big rwhp car, like your turbo car than yes, that extra few mm's probably helps you hook it up - but that's it.

On a stock car, not so much.

But truly, the rate of increased or decreased acceleration is much more affected by the change in rolling diameter of the chosen alternate tire.

Don't forget that when you install a taller-than-stock tire out back, you lose the gear advantage by small amounts; or conversely, if you shorten the tire, you get a little more gear advantage.

Example - going to a shorter tire:

Stock diameter 245/45-18 = 26.68
vs.
Upsized tread AND shortened diameter 255/40-18: 26.03

Delta = 0.65" or 2.43%

Extrapolating: Final drive ratio of 3.54 + 2.43% = 3.63 = net effective rear gear (and/or 2.43% "more acceleration" but bear in mind..... speedo error also equals 2.43%.)

In real world terms, this is really nothing and is picking nits but I just put it out there as an example for people unfamiliar with the concept so they can judge for themselves how a tire change affects acceleration, however minute it is.

But more importantly, so they can see the math involved in calculating how a change to a 3.90 or 4.10 gearset will affect overall performance. IMO, THE best acceleration modification for the money. (Apologize for the tangent but this is a mod I rarely see discussed.... more discussion on acceleration gain typically revolves around "mo'power" and frankly, the Z33's acceleration can be so much improved with a simple gear swap and better utilizing the power it already has.)

Disclaimer: Yes, such a mod does have a tradeoff in higher running rpms (wear and tear plus lower mileage) and a small sacrifice in top end BUT, it's rare for a street car to ever need that top end. Stop light to stop light and/or freeway entrance to exit is a more apt use... and that's where acceleration is key.

Mic

PS 3.90 on an HR equipped car (higher rev engine) is, ahem, the shiznit.

 

As always i learn something. Didnt know that smaller wheels affects gearibg. Always a good read.

And in the subject of gearing, i feel its rarely discussed because its one of the more complicated mods that the average amateur gearhead cant ibstall themself. That along with having to recalibrate the speedo turns it off for many.

My 2 fav mods for any na car is light weight flywheel and gears. It maximizes that power that is already present. Ad tune on too and its a night and day difference.

 

Thank you, Spike, appreciate the confidence. I am humbled.

I was fortunate enough to have "older" (read: "experienced") guys around me to teach me stuff coming up way back when. It's that philosophy I gained from them that makes me want to pass along stuff if it'll help someone build a better, more practical car, or at least help others avoid the mistakes I either made or "almost-made, were it not for the people around me".

Cheers,

Mic

 

Thats it I need new gears...

But honestly I don't really get why people with NA cars are that worried about wider tires, even semi slick in the rain my z doesn't spin tires unless im trying to spin them. Maybe im doing things wrong.

 

I should also mention terrasmak, who is a great and also a very knowledgeable resource for accurate information.

 

^^^ Word!

Find myself coming into a thread after Len and thinking "that's exactly what I would have said!"

Not that I'm right or anything, I just agree with his advice a lot.

There are others as well and I can't/won't get into a mutual admiration fest at this time but they know who they are, including this "Spike" guy.

 

The two sizes are interchangeable IMO, what size I would buy if I were in your shoes would depend on what is available in the tires I was looking at. I would seriously start looking for wider wheels 9.5 shortly after, the 245 or 255 will fit on the wider wheels later