TruPlaya26

iTrader: (4)

So my tires are starting to wear down and I'm almost at 15k miles and I'm starting to have issues with traction. I'm thinking about putting some wider tires on the rear of the RCF, but how wide can I safely go without rubbing too much or putting too large of a tire for the wheel? For reference the stock Michelin PSS that came from factory are 275/35/19 and I was hoping to go either 295/30/19 or 305/30/19 also with Michelin PSS tires. My car is lowered on Swift Spec-R Springs and I have spacers as well (15mm). Has anyone done this, opinions?

ssmoked

I know for sure (confirmed by 3 separate major tire shops) that 305/30 would fit on STOCK height without any rub and 305/35 will rub. If you go 35 series, it will rub for sure when lowered

305 is the max that will fit safely on a 10' rim.

Stock rear is 275/35 not 275/40 as you stated

TruPlaya26

iTrader: (4)

Whoops you are correct I added 5 mm to the tire height accidentally. Ok so now with the correct info and sizes, considering again that my car is lowered on Swift springs, would you recommend 295/30/19 or 305/30/19?

flowrider

iTrader: (9)

305/30 is pushing it, and not recommended. 295/30 will fit just fine. I have RCF wheels on my ISF with 295/30s on the back. I am not lowered.

Look at this chart.

Lou

ISFPOWER

iTrader: (20)

i would stay with a oem sizes on oem wheels. i have a pair of brand new 275/35 conti DW for sale if needed.

ssmoked

you are located in Florida, take it to Discount Tire store and ask for their professional opinion. Visit a few stores if needed.

305/30 will fit for sure if you are stock height (which im doing in a month), but since you are lowered it will be tricky. Maybe they have a special calculator for you. They also have a policy if your tire rubs when installed and lowered to ground (not driving on it), you dont have to buy it.

IMCHIA

For my first tire replacement, I definitely plan on going wider. I'm thinking 275 up front and 295 in the rears. I'm on stock rims. I know our stock tires are:

Front - 255/35 = 255*.35 = 89.25 mm * 2 = 178.5 mm = 7.02 inches + 19 inch rims = 26.02 inches wheel diameter.
Rear - 275/35 = 275*.35 = 96.25 mm * 2 = 192.5 mm = 7.58 inches + 19 inch rim = 26.58 inch wheel diameter

So If we go with 275 up front and 295 in rears. I assume 295 in rear should be 295/30 rather than 295/35 to keep to as close as stock wheel diameter as possible.

Stock Front: 255/35
Stock Rear: 275/35

New Front: 275/30
New rear: 295/30

johnnyreb

I thought smoked said the 305/30 would fit safely on the rear oem wheels, especially if the car hasn't been lowered?

lexusrus

I like this idea with going wider. I'm almost due for new tires too (rear ones).

But for safety reasons I'm changing all four to all seasons tires as I encounter 20 degree or below temperatures sometimes in the winter. If I just change the rears to all seasons and keep the OEM front Summer High Performance tires, then I'm asking for trouble risking loosing my tail breaking traction.

Davew77

I'm running 265/285 Michelin Pilot Sport A/S3+ since I'm working in NC on a contract and my PSS wouldn't grip at temps below 40. I went back to Tampa for a couple of weeks over Xmas and I don't notice hardly any difference in grip between the 265/285 A/S3+ and the stock 255/275 PSS in hot temperatures. In cold temperatures there is a clear difference and the A/S3+ are far superior. You "might" notice a difference if you run the car at the track. But on the street the difference is so minor that I will run A/S3+ all year from now on. They should also last twice as long on the tread wear. I'll keep some PSS on my spare set of rims if I decide to start tracking the car. YMMV

Edit:
As an example of the grip; I've hit 1.0g on the G Force meter in the car on a S-curve here at work while travelling 65 mph. I don't know how much more grip I could pull out of them because I don't want to end up in the ditch.

ssmoked

You dont have to take my word. Either believe 3 independent tire shops that guaranteed me it will fit or take the word of an ISF owner with RCF wheels

ssmoked

I had the A/S 3 on my 370z when it first came out and its a pretty sticky tire on the dragway too. I did my best time with it, with a mild burnout. If you read some reviews on tirerack, under extreme cold temp with snow, it doesnt grip as well compared to other brands. In the rain its great, on the dry it grips close to the PSS
I only got 10000 miles out of them, even though they are rated at 500 threadwear. I will admit I did at least 50 runs on the drag strip and drive pretty hard daily. 3400 lbs 370z curb weight. Only con is they dont make it larger than 285/35

The current 275/35 PSS on the RCF, the cars breaks traction in second gear WOT on a hot day. Its inefficient and not fun. That's why many want to increase to the largest size possible. Going 30mm larger should help significantly. I'm also looking at Bridgestone RE11, as they are grippier and cheaper

Davew77

The drag strip eats tires. When they do break loose on a launch you lose more rubber than you would on the street due to the prepping compound. If you do burnouts to warm them up you will of course lose rubber there too. I got about 20k out of my stock PSS and I am seeing better results from the A/S3+ so far. But I haven't been to the track and I don't usually floor the car in 1st gear, so I don't break loose often. I have never had any issues with my 2nd gear on my PSS until my tires started getting worn and once it got cold grip was almost non-existent. The only time I can remember breaking loose in 2nd is once when I was going sideways in 1st and shifted to 2nd without letting off the gas. I had to let off after about 2 seconds or I would have been in the ditch. I was having fun.

YMMV, maybe road conditions (oil, gravel, etc) or extreme heat (100+)? I know the roads in Socal get a lot of oil built up due to little rain.

ISFPOWER

iTrader: (20)

only person in this thread that is making sense.

Davew77

I'm glad that you approve. Yet, it still doesn't answer the OP's question and the title of the thread... Sense is relative.