Nismo LMGT4 18" rims, 8.5" wide front, 9.5" wide rear. I want to go with Falken Azenis RT-615 tires, but the sizes offered are limited. What sizes should I go with?

Was thinking 235/40-18 F, 255/40-18 R on the '03-'05 Rays rims; would these sizes go ok on the wider Nismo rims as well?

 

I would go with

265/35R18 front
275/35R18 Rear

 

245/35/18 F 275/35/18 R are recomended my nissan for neutral steer and best acceleration.

 

eh, not really... maybe you mean 245/40-18 and 275/40-18? (which BTW, is not neutral at all)

those RT615 sizes don't exist anyway, closest he can get is

245/40-18 front and 255/40-18 rear

personally I would prefer a wider tire with a very slight width stagger f-r, everything slightly underdriven. I would go for 265/35-18 front and 275/35-18 rear

 

i know for 19s that nissan does actually recommend 245/35/19 and 275/35/19...dont know if its different for 18s though

 

Yes, it's 245/40/18 and 275/40/18. Have to have more sidewall to make up for the smaller rim and keeping as close to stock circumference as possible. This stagger is not ideal for neutral cornering, though; it's recipie for understeer.

As for 265/35/18 and 275/35/18... well, I couldn't imagine having tires as wide as my FX35 had all the way around on the front of my Z... sounds like mega heavy steering to me. I'm also NA, so I just don't think I'd need that much tire on my car.

While 265/35/18 underdrives the car by 2.2%, same as a 235/40/18 would, the 275/35/18 rear underdrives by 4.1%, which seems a bit much to me... the 255/40/18 underdrives 2.4%; a much closer match to the fronts...

Hmm, dunno... The car will be a street car, not track, and I want good steering response, neutral handling and good cornering grip for some spirited mountain roud driving; something suitable for an NA car with bolt-ons... just seems like the 235, 255 combo would be my best bet. I know they wouldn't look as nice as big, wide tires on the rims, especially the rear, but they shoud work on them ok, right? As grippy as these tires are supposed to be, less should be more, right?

Anyone else have input?

 

I drive on RT615
255/40-17 front and 275/40-17 rear (on 17x9 and 17x10 on 5zigen fn01r-c) this is my track set.

I also run a set of 245/40-18 and 275/40-18 (on 18x8.5 and 18x9.5 on BBS RGR) as my street wheels (bfgoodrich KDW)

the slight underdrive on the 17" wheels is a great asset in response and performance. Even in everyday drive it has an edge over the bigger fatter 18s (even on the light 18lbs BBS wheels). That is why on my next set I will be moving to the 265/35-18 and 275/35-18 RT615, I'd rather slightly underdrive than go narrower (I just love the falkens).

imho, 235 and 255 are not the best choice for the width of the nismo wheels. (great sizes for the track model wheels though)

 

From my understanding you want the front tire size as close as possible to the rears? First of all unless you like the stretched look go for it. Secondly if you accidentally rub against a curb your more then likely to scratch you rims, (unless of course you have a crazy offset like 50) Last are you really going to notice that 4.1% undedrive issue. I notice the slightest things but I don't think that much is going to make you hate your car. Why are you buying these tires are they local or is someone offering you a good deal for tires and wheels? You do know that discount tire direct carries the 275/35-18 in this specific tire so these are not limited in sizes.

 

Yeah, maybe I'll just keep the track rims, then. 4.1% is just more than I'd want to underdrive the car and I don't want VDC issues with the diff between front and rear.

I'll be buying the tires new; I just want what wil be best for my needs. The 255 might look a little stretched on a 9.5" rim, but not as much as a 275 looks on a 10.5" rim, so I think it'd be alright, though; after all, a 275 is les than an inch wider than a 255. The 275 width would be nice on the rear; just wish they had a 275/40 or 265/40. The 265/35, I'd think woud bulge a bit much on the front 8.5" rim for my liking (plus Falken's site states a min rim width of 9" for the 265/35); I prefer a bit of a stretch as opposed to a bulge that the car coud roll on in hard cornering.

As for curb rash, you'd have to have tires bulging all to hell to avoid it (you'll rash ur wheels just as sure with 275s on the rear as 255s), so I'm not going to worry about that. Maybe they'll come out with more size offerings; I hope so...

One more question: on Falken's spec sheet, what does the "reinforced" next to some of the sizes mean?

http://www.falkentire.com/rt615_sizes.html

 

I run 265/40R18s all around, and LOVE it. No heavy steering, very neutral handling, and fun all around. And I'm NA. I also have Hotchkis adjustable sways that are further biased towards the front end. My only complaint about this setup is the slight overdrive compared to stock. I'm hoping to find a way to fit 285/35R18s on all four corners next time, just have to find a way to squeeze them in the front wells!

If you're sold on RT-615s, I'd vote for 245/40R18s front and 255/40R18s rear if you want to maintain the stock stagger, or you could go 255/40R18s all around if you want to cut down on oversteer.

-E

 

Actually, a 265/40-18 underdrives the car by 1.3% (rear), though they are 1.4% larger in front, it's the rear that counts. As for maintaining the stock stagger, 235/255 would do that, not 245/255. I like the stock stagger; with the Nismo suspension, I'm pretty neutral, very little understeer (I think you meant understeer instead of oversteer). A little understeer is ok and safer on the street. For Auto-X, same size all around is great, though.

I wish they had a 245/40-18 and a 265/40-18; that would be ideal for the Nismo rims, I think, retain the stock stagger and be very slightly underdriving.

 

Same setup I have on my 615's. Very very balanced.

 

You're right, I did type oversteer when I meant understeer. Brain was thinking ahead of fingers.

Well, I guess we have to specify what we're really talking about here My car (an '04 Enthusiast) came with 235/50R17s on the back and 225/50R17s up front - so, for me, a 265/40R18 is slightly bigger around, a very slight overdrive. Your circumstances may differ.

And again, on my car, the stock front tires are .4" smaller than the rears. So to maintain that height stagger, 245/40R18s and 255/40R18s would be the closest match (.32" smaller front than rear). And my width stagger, obviously, is 10mm, not 20mm as some Zs have. So we'd really need to know exactly what year and which trim level we're discussing to nit-pick this arguement to death

Depending on what year and trim level you have, these numbers will change. And realistically, any of the numbers we've been throwing around will work.

I respectfully disagree with the statement that understeer is safer on the street. I'd say that a neutral car driven by a competent driver is safest. Too much understeer and you go off the street nose first, too much oversteer and you go off the street butt-first But that's a discussion for another thread!

-E

 

Agree on the oversteer/understeer thing. Was mainly saying I want to be as neutral as possible and the stock stagger (I ws referring to width, not height) with the Nismo suspension is pretty neutral, so I wouldn't want to dial in more bias to oversteer.

My car is '03 Track, btw. Stock tire sizes: 225/45-18 F, 245/45-18 R

 

Since you are actually running this setup, a few question for you:

1. what rim width are you runnning front and rear?
2. does your car have VDC? If so, any issues?
3. do you have suspension mods?
4. Is the 4.1% underdrive of the rear wheels noticable?
5. got pics?

 

Here's a pic of what the tires look like...



Angled pic with the exhaust...

 

I forgot to mention they aren't nismo wheels they are rotas.

 

You still forgot to mention rim width....^^^ Rota's are probably the most identical if not exactly the same looking wheel as the Nismo's. You also look like your running either an aggressive stagger up front, Rota wheels just concave in like that, or your running the same wheel width all around. Nice wheels by the way.

Doesn't the tire difference have to be a half an inch to an inch different from front to back for the VDC to work properly?

 

Actually he did say he's running 9.5" wheels all around with 265/35R18 front and 275/35R18 rear tires. Only thing he hasn't shared is the offset, which I'm curious about. My 265s in the front on 9x18 +25 wheels look like they come out further than his do, and he's running 9.5" wheels. What are the offsets, 97supratt?

*EDIT*
Oops, nevermind, I just looked on Rota's site and those wheels only come in +30 offset, so they are tucked in a bit more than mine.
*EDIT*

-E

 

Thanks for the info. Couple of your answers make me think those sizes won't work too well for me. 1. front Nismo rim is 8.5"; too narrow for 265 according to Falken and 2. you only have TCS; I believe VDC is a bit more finicky about tire sizes, thus that 4% underdrive in the rear...