Tire size

[SeaPro]

ok so I'm a tire noob.

I've got stock ls 17 inch rims which I believe are 7.5 inch diameter (please correct me if I'm wrong).

I'm currently using 225x55's but have found a nice set of 205x50 R17's. Can I use these tires on the stock rims? I've been searching all day and can't find a direct answer.

Thank you.

 

[joegr]

The rim is a 17 inches diameter.
The rim is 7.5 inches wide.
The factory size tire is 235/50R17.
The tire diameter is 17 + 2 x 1.9685 = 20.937 inches (WRONG)
The tire width is 9.25 inches

The tire you are asking about would be 20.937 inches in diameter (WRONG) and 8.07 inches wide, assuming the tire was meant for a 7.5 inch wide rim.
That seems a bit narrow.

 

[BCA]

Not sure which formula you are using there Joe, but the diameter of the stock 235/50-17 should be 26.25" and the 205/50-17 tire would be 25.07" in diameter.

Width x (Ratio/100) x 2 / 25.4 + Rim diameter

It was a bit late when you were posting.

To the OP,
As for mounting a 205/50-17 tire on factory 7.5" wide rim; the recommended minimum and maximum rim width for that tire is 5.5" - 7.5" so it would be acceptable and it should fit the car with no issues. However do to the difference in height, the speedo will be reading about 3 mph faster than your actual speed.

 

[joegr]

Not sure which formula you are using there Joe, but the diameter of the stock 235/50-17 should be 26.25" and the 205/50-17 tire would be 25.07" in diameter.

Width x (Ratio/100) x 2 / 25.4 + Rim diameter

It was a bit late when you were posting. ...

Yes, that is correct. Sorry about that. It's been a rough several days...

 

[chris2523]

it'll fit, but it'll be pretty skinny and pretty short.
would not advise.

 

[1LoudLS]

the last thing I would want to do is go with a skinnier tire and lose some traction on a two ton car...

 

[Dino'sLSdeuce]

For Information Only
Tire/Wheel/Size/Ratio and 'noticed' Differential ...linked to Traction-control (Forced Reduction in Speed).

Unknown and Un-intended response (only after a while) when I installed different wall-series.
As my daily-driver, I didn't like the stock look of the LS, slightly front-end slanted and the rear-end up (IMO aka...dragster look).
At first I didn't want to fork-over an un-needed amount for lowering-springs on my daily commuter. But vanity also took it's toll...
I just didn't like the front-end dipping or the rear-end haunched up. -My vanity wanted an even and flat-or-leveled look. . .

My 2002 Lincoln LS (3.9L) V8 came with: Front/Rear tires -Goodyear Eagle LS (P235-50-17's) on the chrome stock 5-star's.
So when it came time to replacing my tires I purchased (2) Goodyear Eagle LS (P235-50-17's) for Front and I purchased
(2) Goodyear Eagle LS2 (P235-45-17's) for Rears. This gave my vanity the answer it needed; suffice to say it leveled out. 50 series up-front and 45's @ Rear. Finally the Dragster look was gone.

After a few years I never gave it a second thought. That is until, the tires tread-wear differential between front and rear became noticeable to the car's computer that it signaled a blinking 'Traction' indicator (AT FREEWAY SPEEDS), it will automatically disengage (inop) the accelerator pedal and reduces your vehicle's speed to nearly 10-mph or until it comes to a complete stop, prior to the driver re-gaining (now operable) accelerator (gas) pedal control (as normal).

It only happens when your maintaining a freeway speed and attempt to stomp on the gas pedal. that the traction light blinks and reduces your speed to near 10-mph before your able to re-use the accelerator pedal. This 'disengagement' or 'non-use' of the accelerator (gas) pedal never happens at below freeway speeds (ie...city or 45mph less).

Considering first installed @ 7/32" full tread, I did not notice any probs until the tread-wear was about 3/32" and attempt to over accelerate (at times) at high freeway speeds. It wasn't until, I disengaged the 'vehicle traction control button' prior to entering freeway speeds, I realized the ECM finally found an unsafe wheel differential to trip the vehicle to a safer-speed or until I turned-off the 'traction-control'.

But, I degress my Vanity knows no bounds and as of today my ratio still remains 50/45 (front/rear), it's VAIN but it's LEVEL also.