245/40/18F & 255/40/18R S03's
 

Just ordered new tires from Tirerack. Ultimately I decided to stay with the stock wheels for now and I think going with the wider front tires (now only 10mm smaller than the rears) would help the handling(read: reduce understeer). I actually really wanted to go with the BFG Comp TA G Force KD's but the only sizes you can get them in that fit the stock track wheels are the 225's and 245's. This setup will also give slighty shorter gearing, but only slight.

So, along with my 12lb battery, stripped interior, steel braided brake lines, and Hawk HP+ brake pads and Motul 600, I think I should be in good shape for Laguna Seca!!

Just an FYI...

There's a statement going around here on this site that the difference between the front and rear diameter should be no less than .5" and no greater than .7" to keep the ABS, VDC and EBD in working order. I cannot find this in either the Owner's Manual, nor the Z33 Service manual so take it for what it's worth.

The difference between a 245/40 F and 255/40 R is .3" I'm running a 225/45 F and 255/45 R (a full 1" difference) and thus far have seen no adverse effects, but I haven't pushed it on a track either...

Re: 245/40/18F & 255/40/18R S03's
 

Hey Raceboy,
Are those the steel braided break lines from Stoptech that Monkeyman is selling? If so, how do you like them? How do they feel compared to stock? Do you think is was worth the investment?

Also, why did you choose the Hawk HP+ brake pads?

Finally, what is a "Motul 600"?

Thanks!

Yes, I have the same question. I think the source of that info was the Tire Rack which is who sold Raceboy the tires. Clarification from Luke would help here.

I think the factory size is 0.8" difference. The best tire combo would be:

235/40r18 = 25.5"
255/40r18 = 26.1"

Difference is 0.6" which falls into the bracket.

The diameter would be little smaller than the oe tires... wonder how it would look...

I'm still not sure I know what going to a 235-255/40 combo will do to the "look" factor. Will the tires look better and fill the wheel wells better? Will they look smaller? Bigger? Have a lower profile look? Or is stock size the way to go if you're not changing the rims?

I'll tell you why I don't believe that statement. .2" is simply too close a range. I tire has about 1/3" tread top and bottom. Just from simple tire wear you can fall outside that range. You also need to look at each individual tire's specs and not just try to calculate the difference. Actually, the tire diameter difference of the S03's I got is .5" and not .3" S03 Specs I think the rotational speed difference has to be much higher before the VDC/TCS kicks in.

The Tirerack is great and most of their info is correct, but they make a lot of mistakes too. I have gotten tires from them mounted backwards on wheels before and they said that I would have no fitment problems with my SSR comps on my MRS, but I ended up having to get longer wheel studs to get enough threads into the lug nut.

To answer another ? yes they are the Stoptech lines. I haven't installed yet, but quality looks excellent. Steel braided lines have made a huge difference in every car I have ever owned. I like a rock hard brake pedal.

I went with the Hawk HP+ pads because I do a lot of track events and the Hawk HPS pads aren't really up to it. And lastly, Motul 600 is high temp racing brake fluid.

Are those pads only for track use or are they track/street use?

They are track/street pads. They have a higher coefficient of friction than the HPS pads (.5 vs .4) and can cycle over 1000 degrees without glazing. They will however, squeel when cold.

Well, the tires came and were put on yesterday. I drove them about 100 miles yesterday then put the car away for the night to heat cycle them thoroughly.

OK, this is the tire setup that Nissan should have put on the car in the first place! Looks a lot better. 10mm wider according to the size vs stock, but if you actually look at the specs the 255/40/18 S03 is 9.4" vs 7.9" for the stock 040's. That is a 1.5" increase in treadwidth!!! The fronts go up to 9" from 7.4" stock and the front rear difference is now just 4% instead of 7%.

Impressions: well first of all let me say that there were no VDC problems, ABS (and I did use it) worked just as before as well. Steering is a bit heavier at low speeds with the extra 1.6" of rubber on the road, but it feels fine at speed. Even though I went 40 series the ride doesn't seem to have suffered at all. Now the good stuff; grip is greatly improved!! The 040's are not even on the same page as the S03's. Understeer also seems to have decreased somewhat, but I will have to leave final judgement on that until after 01/30 at Laguna Seca. All in all I highly recommend this tire upgrade to all Track model owners.

I got my 245/45s put on tonight. I know NO ONE will believe me, but that .3" in height makes a lot of difference in ride quality in my car. My Z is nice and stiff again. The 255/45 sidewalls made the rear feel very floaty and not planted at all. IMO, just too tall for the 8" rim. Would have worked well on your 8.5" rears, but not on my 8" rims.

Glad you got what you wanted out of the S-03s. I'm very happy (now) as well. I would have definitely went with the 40 profile in the 255 if they were OK'd by Bridgestone for the 8" rim, but they are not.

It's pretty funny, because even though you went for the same sizes as stock, the S03's actually put over 1" more treadwidth on the road than the 040's both front and rear. It amazes me because they are both Bridgestone tires!

why would a tire the same size, made by the same company be such a different size??

Because the 040 has a narrow contact patch that looks like...

/----------\

The S-03 is...

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Why? My guess is that it's one way to win tire comparo tests when your 245 is bigger than the next guys. Anyways here are the 040 specs and here are the S03 specs. See for yourself.