payne

I have a chance to get 4 255/45/18 Nitto 555s for $280 with 400 miles on them.

Im thinking about picking these up to run on the back of my 18x8.5 or 9s as they seem to be pretty good street tires, and I dont think I can run the 285/35/18 555Rs given my offsets.

The question is will the FD be okay with 255/45/18s on the back with 235/40s or 245/35s up front?

I was thinking about 235/40/18 F1 GS-D3s up front as they are on sale for $167 at the tire rack

I have Cusco coilovers now, so I still will be able to balance ride height without changing spring rates.

I just dont want to run two different diameter tires and mess with the ABS or something...

-Jason

quid

You won't hurt anything if that is what you mean but I don't think it will look good. Typically if you are going wider in the back, you will also go down a series in the rear so the height will remain the same as the tires in the front. If you wrote the numbers above correctly, then the tires in the rear will be taller than the tires in the front and the car will just not sit right. But, that is just me talking. SOme guys might actually like that look. This is typically the setup you would see on an older american V-8. Good luck

Retserof

iTrader: (1)

At some point the ABS computer will react to different rotation speeds of front vs. rear wheels, but I don't know how big the difference has to be for that to happen.

Different front vs. rear tires will also make it harder to predict the car's handling.

joeyz87

Just do alot of burnouts till the rear tires are same height as front.

rynberg

You people are all on crack.

Those tires will not work AT ALL. They are a full 2-inches too tall.

payne

I am already running 245/40/18s on all the corners fine.

The taller the tire, the better, as it effectively lowers the gear ratio.

I'll probably pass on these tires.

-Jason

FLA94FD

I would think that a lower effective ratio would be achieved with smaller tires. That would cause the car to turn more RPM at a given speed. Stick with what you have.

rynberg

245/40s are already an INCH too tall! Are you trying to make your FD look like a truck?

Taller tires numerically lower the gear ratio = reduced torque/hp at the wheels. They also increase unsprung weight, resulting in poorer ride and handling.

Proper 18" tire sizes include: 225/40, 235/40, 245/35, 255/35, 265/35, 275/35, 285/30, 295/30, 305/30

7racer

Please take a pic! I want to see the RX-7 4x4!

7racer

And I agree with rynberg....are you guys on crack!?!?

theantirotor

iTrader: (1)

you people have no idea...


i think he has the hp/torque at the wheels issue covered and his car looks just fine with its 4x4 tires

rynberg

I've got plenty of idea, I know he has an LS-1 conversion. That doesn't change the fact that taller tires than stock reduces the tq/hp being put down on the road.

Looks are in the eye of the beholder, I am coming from a functional standpoint, for which running such tall tires are a detriment. He must have a stock suspension, otherwise he must be hitting the front fender liners pretty regularly.

theantirotor

iTrader: (1)

cusco coil overs = stock? ok....


taller tires change the gear ratio... they do not "reduce the tq/hp being put down"

rynberg

He did note above that he just got the Cuscos...

A taller gear ratio has less torque multiplication, therefore there is less torque making it to the wheels.

Stock FD -- 217 lb-ft at 5000 rpm

1st gear is 3.483:1, rear end is 4.1:1, final drive = 14.28:1 = 2999 lb-ft @5000 rpm

Stock FD running 255/45 18 tires

1st gear is 3.483:1, EFFECTIVE rear end is 3.76:1, EFFECTIVE final drive = 13.1:1 = 2842 lb-ft @ 5000 rpm

The taller wheels reduce the effective torque at the wheels by ~5%. Probably academic given the LS-1, but the larger wheels will reduce the effective torque/hp to the ground. Assuming he's making 400 ft-lbs (modified), that's a loss of 20 ft-lbs.

payne

For one thing I just got the Cuscos installed in the last two days. Car is still on jacks while I finish my SS line and HP+ install.

Secondly, I am running these tires because I got them with 18x9 volks for $900.

Lastly, I really want as large a tire as possible, as with the stock diameter, I would much rather have 3.73s or something like that. I can only trap like 118 or something with a stock diameter wheel at 6200 rpm, and I should be faster than that at the strip when I get everything done.

-Jason