UncleSpud

Can you safely upgrade wheels/tires on an IS 350 F Sport without screwing up traction control and throwing a CE light? Does the IS 350 measure wheel spin between front and rear tires? Or can I simply use a tire size calculator and choose the wheels and tires based on results of going plus one?

Also, Tire Rack shows nothing for tire/wheel upgrades for the '14 350 F Sport. I realize it's a new car,
but I find that a bit worrisome.

Any thoughts?

bnizzle87

You'll be fine for the most part. It also depends on what you're trying to achieve. Some may choose to have a stretched look, while others want something that is larger and fits just right. Club Lexus, on its Tires, Wheels, and Brakes forum, has an actual calculator to use. That I didn't know before I upsized both wheels and tires.

Just find out the rolling diameter first and go from there. That way, even upsized, you should have the the same circumference and it won't affect the spedometer much or even at all if you keep it close to the OEM specs.

Best of luck!

Bass Mech

I put a lot of time into the same question and I'll save you a lot of time.
235/35/19 front 275/30/19 rear
These tires are wider and slightly taller. The factory speedometer reads about 1 mph high so the larger tire will fix that.
Also these sizes are within .2% of the exact sane height front to rear
I have not mounted the tires on the wheels because I don't have the car yet. But look for pictures next week. I've put nearly 2 full days time into researching this issue and I feel confident this is the perfect tire size for 19" wheels

F350

iTrader: (1)

that's the exact tire set-up i'l be using as well on 19x8.5 / 19x9.5 rims i'll be putting on soon

felixlau

I'm running 225/35 R19 & 265/30 R19 and I felt a lost of low end torque.
235 & 275 will give better road holding but may sacrifice some low end torque

Bass Mech

That's all in your head, your not going to notice .25" in tire height
But your 265 rear is shorter than the front so you might be activating the traction control easier because the rear tires are already spinning faster than the front

felixlau

Not tire height causing the "drag" in acceleration but the wider tyre in contact with the road.
I started with the original 17" 225 and the jump to 19" 265 was quite a lot more and I felt the difference especially at low speed.

felixlau

I think the front and not the rear is shorter

Bass Mech

NO a 225 front is close to a 265 rear as your showing i was saying that your 235 front and a 265 rear will have the rear smaller than the front.

a 235 front and 275 rear will be a lot better match.

felixlau

Agree
Btw, mine is the 250 , no 350 available here, so I guess the extra horses and torque u guys have will not suffer any loss of torque .... And as Pirelli says.... Power is nothing without control !
If given a choice again, I would opt for the 245 instead.

UncleSpud

Your loss of torque may be due to increasing the car's unsprung weight by going with heavier-than-stock wheels and tires, although that's not always the case. I recently went from a 235-55-18 OEM tire/wheel combination on my Mustang to 255-40-19's (using fairly heavy wheels) with no perceived performance penalty (of course with approximately 390 RWHP, the loss wouldn't be as noticeable). I wouldn't want to slow down the 350F though, so I'll look for lighter weight wheels.