I have a 1991 Pontiac Trans Am with 245/50/ZR16 tires on the OEM 16" wheels. I recently purchased at a swap meet a set of 4 15 X 8 rims off of a 1986 trans am. My purpose here was to get (4) blizzak tires and mount them on these rims so I can swap them out with the 16" OEM wheels during wintertime here in PA. My question is will this work and will I have any issues with the Offsets ?

Anybody who has done this or have better snow tire ideas would be most appreciated.

Thanks alot.

 

Will bolt right on and should work very well. Hope that car has posi up there in the snow.

------------------
91 Camaro RS 5.0L Black Convertible 700R4
** Added so far **
*GM Wonderbar,Alston SFC's,spohn LCA's and Panhard rod
*Turbo City Inj Spacer
*Dual Snorkel Air Filter
*March Performance Pulleys
*GM 3.42 Gears with OEM Zexel POSI
*Edelbrock headers
*3" High Flow Cat
*3" Dynomax Exhaust
*Walbro 255 lph Fuel Pump
***Future 330hp Vortec Crate with LT4 hotcam and 454 TBI

 

Thanks alot for your reply. Does anybody know how I can figure out how the speedometer will change in accuracy going from 16" wheels to 15" wheels ?

Thanks again...

 

Rim size has nothing to do with the speedometer, it's what size tire you put on them. As long as your tires have the same outside diameter the speedo will read the same.

 

So if I were to change a 15" rim running 215/65/R15 to a 16" rim or 17" rim, what size tire would I have to get to maintain an accurate speedo?

 

245/50R16 on the 16 (assuming 8" or wider)
275/40R17 on the 17 (assuming 9" or wider)

 

Just an FYI. To find the diameter of a tire such as 215/65/R15, use the following formula. The first # is the section width in millimeters. Multiply that by .03937 to convert it to inches. 215mm * .03937= 8.4645". Next multiply 8.4645" by the next #, which is your profile. This is the height of the sidewall shown in % of section width. 8.4645" * 65% (or .65)= 5.50...". That is only one part of the diameter though. Mutiply that by 2, for both the "top & bottom" of the tire. 5.5" * 2= 11". Then add the diam. of the wheel. 11"+15"= 26".

Now realize that this doesn't take into any consideration the loss of height due to weight on the tire. That will be affected by air pressure (more air equals taller tire), the sidewall stiffness (lower profile means stiffer sidewall), and rim width (wider rims will spread the tire out which will lower the height). Too many variables to calculate exactly, but the above method will give you a general starting ground for exchanging tire sizes the correct way.

Again,
Section Width * .03937 = X.
X * Profile Percentage = Y.
Y * 2 = Z.
Z + Rim Diam. = Tire Diam.

Easy as X,Y,Z.
Give a man a fish, feed him for a day. Teach a man to fish...... YADDA YADDA YADDA!!!

 

Yeah, I've seen the formula before. But it's so much easier carrying around a tape measure.

 

go to www.tirerack.com and look up the sizes you wanna know about and click on its specs, it will give you all the info you need

 

AJ, that one actually gave me a headache.

How about:

215/65/15

215 * 65 / 2540 = 5.50 (Heigt of one sidewall)

5.50 * 2 = 11.00 (Since there are 2, top and bottom sidewalls)

11.00 + 15 = 26" (Adding the size of the rim)

This way, you only have to remember one number, 2540.

------------------
1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

Whatever. SIX OF ONE, HALF A DOZEN OF THE OTHER!!!!!!! Sometimes man, (Or I could say "man, sometimes"!!!) I guess I'd just be better off REMEMBERING that when I try and explain something on here to help, that there will ALWAYS be another person (who should have probably helped in the first place) who has a "BETTER" way. Then why didn't you explain it to him the first time?

I know, why don't you just dial "0" next time you want to call someone? That way it's the only # that you have to remember. Well ****. But then you'd have to remember the person's name. WTF?

You remember what you want. I'll remember what I want. And MAYBE, JUST MAYBE, we can all get along!!!!!

Or you could do 215/25.4 *.65 *2 + 15. Or you could just.................YADDA YADDA YADDA!!!! High road, low road, Scotland before ye!!! Tomato, tamato. P*ssy, ******. Need I say more?

[This message has been edited by AJ_92RS (edited June 29, 2001).]

 

Uhh....I did explain it to him the first time....the first time I saw this thread. You dont see an earlier post by me telling him to figure it out on his own, do you?

And I cant remember the last time I dialed 7 digits to reach anyone. That's what the single digit memory keys are for on my cell phone and cordless phone.

Just because someone offers a different (and maybe easier) way doesnt mean you have to get all bent out of shape.

------------------
1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

[This message has been edited by Omar (edited July 17, 2001).]

 

It was all intended as a joke. Hense the smiles. I wasn't bent out of shape. Chill homie!

 

Cool. Neither was I.

------------------
1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

Unless you prefer ******* and balancing your own tires, it's probably easier just to let the guys down at the local tire (goodyear in most cases) shop and let them figure it out. These guys eat sleep and dream tires, they know the sizes by heart and it's thier job to give you the right tire... All you need to know is what width tire you want and don't let em **** you up the *** with the prices...

------------------
1984 Firebird T/A
305 LG4
T5 - Hurst Short Shifter
Edelbrock 600 CFM Performer Carb
Open Element Filter
Gutted Cat - 3" Exhaust to dual 2"
IROC 16x8 Wheels

 

I have a 91 RS with the 245/50R16 tires on the factory wheels. I got a good deal on a set of 91 RS 15X8 wheels and 215/65R15 tires so I could drive car while refinishing factory 16" wheels. I set them side by side and there was minimal difference in height.

------------------
91 Camaro RS 5.0L Black Convertible 700R4
** Added so far **
*GM Wonderbar,Alston SFC's,spohn LCA's and Panhard rod
*Turbo City Inj Spacer
*Dual Snorkel Air Filter
*March Performance Pulleys
*GM 3.42 Gears with OEM Zexel POSI
*Edelbrock headers
*3" High Flow Cat
*3" Dynomax Exhaust
*Walbro 255 lph Fuel Pump
***Future 330hp Vortec Crate with LT4 hotcam and 454 TBI