So I have 650hp 350z .. just got new wheels 18x9.5 +20 and 18x10.5 +20 .. (stock 245 18s ) ain’t holding in any gear .. what size do y’all recommend ? And was looking at Indy 500 or r888r

 

305/35-18 would be the rear you want .

 

Thanks , will that fit on my wheel or have to roll fenders ?

 

Two separate questions. Yes, it will fit. Yes, roll the rears.

 

Sorry , and thank you really appreciate It . Last question what would u suggest for tires ? As in r888 or Indy 500 or ?

 

i have run michelin pilot sport 4s on both corvettes... no complaints with them at all

 

the Indy 500 tire is in a different league. Great for daily driving, not so much for a 600 Hp monster

 

Those got brought up a lot as well when I talk to people about tires.. will look into though too thanks

 

Ok y’all I decided to go with pilot sport 4s .. widest the comes in 295 .. what size should I make the front to keep the speedo close to normal ?

 

I have 60,000 miles on my car.

I've tried Kumo, Toyo, Pilot Sports, and now BF Goodrich KDW's (no longer available)

https://my350z.com/forum/wheels-and-...ml#post9513000

My favorites are the KDW's (no longer available)

The Pilot Sports were ONLY good in warmer temperatures. If you drive your car in below 45 degree weather (at all) they do not grip the road very well.

I can't answer your question for 305/35/18 but I can give you this:
https://tiresize.com/calculator/
There are two TABS . . . Click on the Tire comparison tab. Ideally, you want to find out the difference between specifications on what your car came with stock between the front and rear. You should maintain this difference on your new tires if possible, else your tire slip light will illuminate.

 

exactly what I needed , thank you this is very much appreciated.. and as far as driving in below 45 degree .. I won’t be taking the car out that cold .. it’s a fun summer car and once I start to see 40s she done for the year but do appreciate the input it’s good to know

 

speedo is of the rear

 

got ya .. so what are people preventing when they make sure the front and rear aren’t so far apart? As in I know people use 245/40 in front and 275/35 in rear a lot .. so I’m guessing 265/40 in front and 295/35 / 18 in rear should be about the same ?

 

I run 265/295/35 x 18 on my street Z. MPSSs, and the steering is very heavy. No problems with TCS. You want the same or larger sidewall in the rear, not front.

 

Do you have VDC or TCS? VDC is massively affected by wrong size differential F-R.TCS somewhat but not quite as tempermental. VDC and TCS both function based on wheel speeds and the ECU is expecting a F-R wheel speed differential of 3% +/- 0.25%. Anything outside of this is seen as tire slippage; that is, if, say, the rear tires are too small, it will register higher wheel speed than the front and that's seen as a "no grip" situation, triggering VDC to cut power until slip is reduced. If the tire is physically smaller, the ECU will never see the correct wheel speeds until changed.

S'far as sizing for speedo accuracy, start with stock sizes (which I literally just posted this morning in a sep post):

Stock 18s and tire diameter (in inches)
225/45-18 25.97
245/45-18 26.68

This gives you the guideline. Now look at your 295 tires...

295/35-18 26.13 (-0.55")
295/40-18 27.29 (+0.61")

Neither are optimal and both will affect speedo read; but not massively. Choose one THEN choose your front tires by their diameters (below) to maintain the stagger/size 3% differential front to rear.

245/40-18 25.72
255/35-18 25.03
255/40-18 26.03
265/35-18 25.30
265/40-18 26.35
275/35-18 25.58

If you do the math taking your desired rear height of 26.13" (295/35-18) and subtract 3% to get your optimal front tire size, you have 26.13 x .97 = 25.35". Looking at the list of tires, obviously 265/35-18 is closest fit diameter wise. But, mind the wheel width to tire size. Optimal fit for a 265 is 10" but you can run a 9.5 and still be OK,... not optimal for performance but its workable.

Back to the OP, I have had good luck with the Conti Sport Extremes on my non-Z. Doesn't have 650bhp but still manages about 425 wheel. I have never broken them loose under power or in the twisties. Love 'em.

.

 

thank you so
much that makes a lot of sense .. I don’t have vdc or tcs as I have a stand alone ecu .. still have the body module if they make it trip but this def tells me what I need I will look into the conti tires

 

So I just got my car done and hit 640whp and the stock 245s all season tires def ain’t holding .. I know the r888r are the go to but 2 questions
1 - what tires y’all 600+ people running for street that hold or close to it
2 if I put r888 in rear do I need matching in front or can I put Sonthing like Michelin ps4 in front ?
by the way my new wheels are 18x9.5+20 and 18x10.5+20

 

Ps4 don't even hold the power in my vette, might be okay in front

 

First of all want to thank y’all for the help over the past 5 years , y’all been awesome . So question 600-650whp what rear tires would y’all go with for the street ? I want r888r but will a 275 hold thag ? 295 ? I want the 305/35/18s but there no sign of them .. all keep saying back order with no date . I have daily driving tires MPSS but looking for sonthing to hold 1-2-3rd gear .. looking for what y’all use and find to hold that power and what size y’all using .. i can buy different back wheels so let me know tire abs size 15s-18s

 

How are the Michelins doing and what size are they? This car isn't really meant to hook like that, most people I've seen with that power are usually on drag radials. I went with 19s, no wide choices for 18s, but my power goal is lower and I want street tires like a normal human being.