I always forget what each number means. Could somebody help? I know my tires are P235/55R16. Also, what is the best tire size for stock wheels? I know that in the new CHP they said the biggest you could fit on 16*9.5 rims are 255/55. I need some new tires and I'd like to get the best size for my stock rims. Oh yeah, and I do know that stock size is 16*8. Thanks guys.

 

235 is the width (in millimeters) of the tire tread.
55 is the percentage of the overall height of the tire that the sidewall takes up and the 16 is the height of the wheel itself.

You can fit much wider than 255 on a 9.5 inch wheel, I've got 255 on my stock wheels. I might try 265 but thats probably pushing it.

 

Whats the widest you can put on a 15x7 without the sidewalls sticking out too far?

------------------
1987 Camaro Sport Coupe 305 V8 LG4-rebuilt-All Stock.

Future Mods: Flowmaster American Thunder 3 in. Cat-back, Catco High Flow Catalytic Converter, Hooker Super Comp Shorty Headers Jet Hot coated, K&N Air Cleaner, CompCam 264H, White Paint, IROC wheels, Alpine CDM-7871 CD player, Polk Audio speakers, Grant GT Rally Steering wheel,New Fuel Pump, Ground Effects, B&M Megashifter

 

If you have the stock wheels and want to use
Z/V rated tires, go with the stock size
245/50/16. Unless you want All/Season
tires stick with what you are now using.

 

This is not 100% correct.


* The 235 is the width in millimeters as stated.
* The 55 is the sidewall height as a percentage of the WIDTH of the tire.
* The 16 is the rim diameter

Oh, and yes, you can definitely go wider than 255 on a 9.5" wide rim. I have 275 on mine..


Ken

------------------
1986 IROC-Z Conv't
- White Gauges, 17x9.5 TT II rims w/275/40x17" F1s, 1.5" Jamex Lowering Springs, BMR stb, Lakewood APR, PST suspension parts, Edelbrock Trailing Arms, KYBs, Edelbrock RPM Cat-Back, Edelbrock JHC Headers, Catco, World Products Heads, CompCam, SLP runners, Ported Plenum, K&N, Airfoil +polished/billet dress-up stuff
ChevyKen's Cars

Administrator @ ChevyWorld.net

 

Ok, I've got another question. I just got 245/50's all the way around. Someday I'd like to go bigger in the back, after total car mods are done. It will see mild strip action and autoX but will mainly be daily driver. What would be a good size for the back on stock wheels?

 

I'd say 255's if you really want (on 16x8's) but no bigger... if you get any bulging on the sides its gonna hurt your cornering more than it helps... bulge is only acceptable for flat out drag racing.

 

I didn't want too much bigger so I'd probably go with the 255's, now what would I want the sidewall to be, 255/what? Thanks.

 

255-50-r16 is the closest you'll get to the stock height 245-50-r16. You can also go with a 265-45-r16, but the only things i'm aware of thay are made in that size are Kuhmo autocross/road race tires.

 

Whats the widest I can get on mine? I currently have 245 50 R16's. I don't want to mess up the speedo, so I want to stick with 50's right?

------------------
New owner of:

1989 Camaro IROC-Z
5.7L TPI
Ravin' Exhaust
K&N's
My 1989 Camaro IROC-Z

Previous owner of:

1992 Camaro RS
5.0L TBI
K&N Airfilter
My 1992 Camaro RS

 

To stay close to your stock size sidewall do a little math. Say you are going from a 225/70-15 tire to a 245/?/15 tire and you want to maintain ride height and not affect your speedometer. Well 225 x 70% = 157.5mm and 245 x 65% =159.25. That is treadwidth x sidewall percentage. Try to stay within 5-10mm to maintain stock setting. You can also use the same formulas in changing rim sizes. Convert the rim sizes say 15 inch and 16 inch into mm. A 15 inch rim is 381mm and a 16 is 406mm. So when going up to a 16 you would want to decrease the sidewall relative height by about 25mm or the inch difference. That is how you can go from a 70 series tire on a 15 inch rim to often a 50 series on a 16 rim. Remember it is all relative to the wheel width. Good Luck!

------------------
87 TA, 305 TPI, Custom CAI, K&N, ACCEL 8mm wires,ACCEL Super-coil, ACCEL Plugs, JET TPI Airfoil, Cherry Bomb Muffler, 160* thermostat
The Phoenix Project..click to see my project car
Trans Am stuff and GIRLS, GIRLS, GIRLS!!!!!

 

Goodyear recommends putting a 245 tire on a 7.5 inch rim. Remember the rim width will effect bead contact. You run the chance of breaking the bead and rolling the tire off the rim if you have too much "bulge". To put the large tire on the smaller rim you are pulling the rubber inward thus you have less bead contact on the rim.

------------------
87 TA, 305 TPI, Custom CAI, K&N, ACCEL 8mm wires,ACCEL Super-coil, ACCEL Plugs, JET TPI Airfoil, Cherry Bomb Muffler, 160* thermostat
The Phoenix Project..click to see my project car
Trans Am stuff and GIRLS, GIRLS, GIRLS!!!!!

 

Here's a list of tire sizes with a very small speedo error (2% or less), or even 0 speedo error:

245-50-R16
255-50-R16
265-45-R16
275-45-R16
285-45-R16
295-40-R16

the real problem is finding tires in these sizes. a few of the sizes just aren't made, and a few are only made in autocross/road course tires. The only one readily available is the 255-50-r16.

 

or if you're into drag only tires, the mickey thompson ET Streets have two offerings which are really good for thirdgens:
26" tall x 10.5 wide for 16" rim.
which is something like a 265-50, and
26" tall x 11.5 wide for 16" rim.
which is something like a 295-40.

 

Is it possible to mount 295/50/16s on the stock rear 16x8 Iroc rims? In the tire's description, it says that it is safe to mount it to anywhere from 8-10 inches. Hmm... I am looking to put those on the rear and 215/50/16s on the front. Thanks.

 

with all these wider tires...do you need to increase backspacing? add spacers? i've seen pictures of the old transam races and the road cars there have really fat rear tires! they look very cool!

 

Maybe this link will help......
http://www.1010tires.com/TireSizeCalculator.asp

 

blast from the past.. wow.

moving to (now) proper forum..

 

That's good, though. It means people are searching instead of asking the same thing over and over and over....
Thank You crazyrinningiroc! And
Welcome to TGO!