westpak

iTrader: (19)

Luke,

I am going to put the 18" Rays wheels from the track model on my car and use the stock 17" wheels for track/autox, I was interested in Kumho's for both sets, the MX's for the Rays and the V700 for the 17"s

The sizes available for the V700's are:
335/35/17
205/40/17
235/40/17
275/40/17
225/45/17

Only options for front are 235/40 or 225/45 and for the rear the only option is 275/40 based on the differences in diamters, wheels width and the intended use which would you suggest.

And for MX's:
215/35/18
265/35/18
275/35/18
225/40/18
235/40/18
245/40/18
275/40/18

I was thinking of going with the 245/40 in front and 275/40 on back. There has been a lot of talk on how wide to go with the wheels so any help is appreciated.

Driven

I'm probably not the one that should be commenting...but what the hell, I've read enough of these posts that my feedback may be warranted. From what I've read, the 275/245 combo you mention on the track wheels for daily driving should look sweet and be the correct size option of what you list. For the 17's and autox you may want to consider a different tire purely from a size option standpoint. I haven't looked to confirm the limited size options you suggest in this tire, but you certainly cannot stuff a 335 on that wheel (nor would you want to) nor should you stuff even the 275 on that narrow of a wheel (again...from what I've read). Additionally the diameters are off from stock...but if it's purely for track....and the rpms are where you want them, who cares? But I don't think your remaining options are optimal. It seems I've been reading of others running 245's on their stock 17 rears and 235's on there fronts. Most guys are reporting better performance with less of a stagger between front and rear. Anyway...food for thought.

westpak

iTrader: (19)

Thanks for feedback, on the autox tires those are all that are available from Kumho on the race tires so not much option, maybe Luke can suggest another brand that is comparable in price to the Kumho's.

As for the Rays, I agree that the 245/275 combo sems to be it, just wanted confirmation that the 275 is OK as Kumho's site recommends 9 in wheels.

Driven

some guys are stuffing 275's on their 8" wheels and saying they "look" OK...but I wouldn't. On the Track wheels I think you are well within the acceptable limits with the extra .5 inches.

Luke@tirerack

the wheels you are using are 7.5" front and 8.0" rear so here is what I would suggest:

225/45ZR17 KUMHO VICTORACER V700 137.00
245/45ZR17 KUMHO VICTORACER V700 138.00

Here's why:
your size list

335/35/17 ..... won't fit the car

205/40/17 ..... just not a good size choice

235/40/17 ..... minimum wheel width of 8.0" and 24.2" diameter not a good choice for the car

275/40/17 .... minimum wheel width 9.0"

225/45/17 .... good front size

your 18" wheels are 8.0" front and 8.5" rear
rear tire diameter should be 26.3-26.8
front tire diameter should be 25.7-26.2
the diameter differences should always remain at the same ratio

your list for the MX's:

215/35/18 .... not a good choice (rather narrow)

265/35/18 .... rear only size with a 25.3" diameter (too short)

275/35/18 .... rear only size with a 25.7" diameter (closer but not close enoughand requires a 9.0" wheel)

225/40/18 .... front only size with a 25.1" diameter (short)

235/40/18 .... front only size with a 25.4" (getting closer)

245/40/18 .... good front size but should be used with a 265/40-18 rear and the MX is not made in that size

275/40/18 .... minimum wheel width 9.0"

there are other possibilities but the tire model selection and wheel sizes are a limiting factor in your scenario

westpak

iTrader: (19)

Thanks, that is what I was afraid of, can you suggest based on the wheel widths what is the maximum tire width for each wheel?

17x7.5=___
17x8=___
18x8=___
18x8.5=___

Luke@tirerack

cool ... a fill in the blank question ... I always liked those better than the essay styled questions when I was in school.


17x7.5= 225/45-17 best but, 235/45-17 possible
17x8= 245/45-17 best but, 255/45-17 possible
18x8= 225/45-18 best but, 255/45-18 possible
18x8.5= 245/45-18 best but, 265/45-18 or 255/40-18 possible

TCL

Would 235/45/18's work on the front?

Luke@tirerack

yes but you would need to go to a 255/45-18 rear and that combo would actually make your car a little slower accelerating because of the diameter difference so, I would not recommend it.

Driven

Hey Luke,

Since you're visiting this site...can I ask you a question? I'd like to run a 255/285 combo on my 18 x 9 and 18 x 10's....and I like the Toyo's. The 285/40/18's should be good cause they are only a little over 1.1% out of spec and produce less than 1mph error at 65mph. Yes, I know I might lose just a hair acceleration due to larger diameter...but I am supercharging eventually which will more than make up for it. So on to my question: If I choose this tire out back, what would the implications of running a 255/45/18 up front be? It's 27" diameter would be identical to the rear...it would fill the fender a bit better than stock...it might wear just a bit longer....and it might ride just a little softer, right? The additional benefit would be the additional .5" clearance under the damned chin that I keep bumping! What do you think?

Luke@tirerack

I think that while your arguement has merits it is a bad idea because the onboard computer system of your car is desgned to read tire speed or revs per miles to control the ABS and traction control system and by having the larger diameter front tire the system would see that as the rear tires losing traction thus activating the traction control system while accelerating and driving at a constant speed and ABS concerns when braking

Driven

Damn you're fast!

OK...I understand your concerns...but don't understand the logic behind them. You are saying the 285/40/18 is a bad size idea, or just the front? And how exactly would the front larger diameter give a false reading to the system that the rear is loosing traction? That part really doesn't make sense to me. Unless the rears "actually" break loose and there is excessive wheel spin I don't see what other input could be a factor. I do, however see your point with the antilock brakes...maybe...because there is more rotational mass? But once again, it seems logical to me that the sensors only read when the tire "stops" rotating suddenly relative to other inputs which again doesn't seem to me would have anything to do with the diameter of the tire? Can you give a lehman's explaination of these funtions to better explain your concerns? And are you recommending the 285/40/18 combined with a 245/40/18 instead? Isn't this a broad spread front to rear?

Thanks

Luke@tirerack

your car currently has a taller tire in the rear that has lower revs per mile (680) because of the additional diameter when compared to the front (804) ... now if you increase the front diameter without compensating the same amount in the rear you car will sense a rotation speed that varies from what it is supposed to see. In your situation the tires sizes both have a 27" diameter instead of the .7" difference the computer knows so the revs per mile will be the same (770) ... you systems will see this as the rear tire spinning faster than it should and "think" that you are losing traction and will adjust accordingly. The current setup has 804 revs per mile in the front and 680 revs per mile in the rear as opposed to 770 revs per miles on all four corners as in your example .... Basically the car needs to see a difference of 124 revs per mile. I hope that this makes it a little simpler to understand.

Driven

Yeah, makes more sense. I had no idea the system worked that way! Anyway, then what is your recommendation? I don't think Toyo T1-S's come in a 265/40/18 which would be the closest matchup. I could live with the 275/245 combo....but really want the 285...so what match would you suggest....or what tire would allow me to accomplish this?

Thanks

westpak

iTrader: (19)

Why couldn't we have same sizes all around too many factors to consider and I am getting a headache. Here is another one since I have an Enthusiast with 17 in wheels and I am going to put on the Rays from the Track model I thought as a minimum I could put the stock tire sizes which are 245/45/18 in the rear but here are the specs and differences from the stock 17's which are 235/50/17:

235/50/17
Dia=26.3
Rev/Mile=769
Actual speed at 70 mph indicated=70 mph

245/45/18
Dia=26.7
Rev/Mile=756
Actual speed at 70mph indicated=71.14

Now that you brought up the differences in Rev/mile and the effect on traction/ABS what is an acceptable difference between front and back and other than a ticket any other things we need to worry about?

It's just tires!!!! Oh my head!!!!

Driven

Westpak, you bring up an excellent question (or at least I think): Are each of the different models actually containing DIFFERENT computer systems specifically taylored to their tire setup? If not, then we have our answer to how much variance even Nissan allowed for, right? I guess that really is the nuts and bolts of it...we all know how to try and get the closest setup relative to stock...but no one seems to know what variance is acceptable...or at what point the system reads an input that is beyond tolerance and applys undesired braking etc....how the hell are we going to get this one answered? Anyone know a Nissan tech? I'll anxiously await this answer before ordering my tires!

rodH

iTrader: (2)

NO WAY ARE THEY DIFFERENT, many car companies are off up to 4 MPH at 60 MPH (reading on speedo). a 1-2 MPH difference is NOthING at 70.

westpak

iTrader: (19)

Well I ended up going with the Toyo Proxes T-1S's and with sizes 245/45/18 in front and 255/45/18 in rear and no problems so far see here for pics:
https://my350z.com/forum/showthread....threadid=18969

2003z

iTrader: (7)

for your autocross tires, I saw a car running the Hoosiers in 245/40-17 at all 4 corners on stock wheels. (might have been 45s) VDC shouldn't matter as it will be turned off.

westpak

iTrader: (19)

They are probably 45, I was looking at those as well as the Kumho's V700's in the same size 245/45/17 mainly because I think the Kumho's I could at least drive to the event and not have to carry wheels but I don't think I could do that with the Hoosiers and have them last.

Then the next question, the Kumho's come in standard tread, shaved and heat cycled, which one to get? is the extra money worth it for the shaved or heat cycled and I would be interested more in durability than added performance because I think they will be so much better anyway I don't want to add more performance at the expense of durability.