hello, i've got real chip a set of chrome wheels from an olds. cutlass that are now on my 87RS camaro, the tires are too big, P245/60 SR15, my speed indicates 10%less and the front does touch on the car when on a curve, the rear doesn't touch.
what size do you guys recomend
also is there any site where i can go to learn what the hell those numbers mean? i can't make any sense of that (p254/60 sr15 and so so so)
thanks to all.
fernando

------------------
third gen muscle power is the only thing that can match the power of flight...

 

sorry i've forgot to mention, the old tires are 205/70 R15
thanks again.
fernando.

 

245 is the width of the tread in mm. 60 is the percentage of the width and describes the sidewall height. S is the speed rating, R stands for Radial and 15 is the inside diameter of the tire in inches. The whole goal is to get the outside diameter of the tire to be the same as the old tires. Hope this helps.

------------------
'89 Red Formula 350- 350 .060 over forged pistons 232* @ .020 cam Performer RPM Holley 750 DP Vortec 1.94 1.50 Accel Coil and dist. Hedman shorty headers Dual Exhaust w/ cutouts 1LE WS6 suspension, wheels, and brakes, 9 Bolt 3.27 Posi Edelbrock LCA's & Track bar subframe connectors 700R4 Harwood snorkel scoop Eclipse Head Unit Delco Bose Speakers 2 12" Pioneer subs w/ 400 watt/chanel amp

[This message has been edited by ATOMonkey (edited July 19, 2001).]

 

thanks monkey man, so you mean...a set of 245/70 r15 will have the same outside diameter? therefore it will fit?
fernando.

 

no, no, no....245 is the WIDTH in mm. The '70' means the sidwall height is 70% of the WIDTH(245). 171.5 mm or 6.75 inch of sidewall. take that times 2 since the sidewall is on the top and bottom. 13.5. Add that to the diameter of the wheel(15). 28.5 inches tall--too big. 235/60's will fit good. 215/65R15's are a stock 3rd gen size for 15 inch wheels.

------------------
350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, current red metallic paint. Lots of other stuff...
82camaro

 

thanks man, 235/60 R15 will be.
the others (205/70R15) compared to what i have now...they look as wide as bicycle tires.
fernando.

 

Just another FYI. The 245 mm is the "section width", not the tread width. Section width is the most outter part of the tire on the sidewall. This has little to do with tread width. Tread width will usually go up when the aspect ratio (60) goes down. The shorter the sidewall height, the wider the tread. The taller the sidewall, the more narrow the tread (usually). But try not to get the 2 confused with each other. Although I probably just confused you more.

 

thanks AJ.
so what kind of formula should i use to end up with a tire that will be:
1-total diameter = 26"
2-thread width = 8"
3-on a wheel 15" x 8"
thanks to all again for your help.
fernando.

------------------
third gen muscle power is the only thing that can match the power of flight...

 

Tire diameter can be calculated like this...

W = section width IN INCHES. Convert to inches by dividing by 25.4
A = aspect ratio as a real ratio, not a percentage. This is easily done just by placing a decimal point in front of the percentage (ie 70 = .7)
r = Rim size

Diameter = r + 2 * (W * A)

So if you want a 26 inch diameter on a 15 inch wheel...

26 = 15 + 2 * (W * A)

We can reduce this to
W * A = 5.5

As was stated before, Section width and tread width are two different things. Section width is a standard measurement. Tread width, while still a standard measurement, varies from tire to tire with respect to Section width. However, a section width about 1" wider should get you around the tread width you're looking for, so if you go with a 9" section width, you're looking at a 225-235 section width.
A 225/60R15 or 235/60R15 tire would get you close to 26" overall diameter.

I brushed over some of the metric/English conversions there. It's easy to convert though. Divide by 25.4 to go from metric to English. Multiply by 25.4 to go from English to metric. 1 inch = 25.4mm It would probably be easier to figure out by converting everything to metric, but everyone has their own preference.

My recommendation for the best setup though would be to get some 16 inch 3rd gen wheels (either off an Iroc or Trans Am, whatever your preference) and go with 245/50R16 tires. Looks better, better traction, better handling. That'll keep you very close to the 26" overall diameter you want to keep also. You could also get some 17 inch fourth gen wheels and the appropriate adapters and go with 175/40R17 tires, but that usually is a pretty expensive upgrade. Those wheels go for around 800 and up on Ebay, and the adapters will run you another 200-300 bucks unless you can have somebody make some for you, and 275/40R17 tires aren't that cheap either. Those wheels and tires WILL fit under the 3rd gen wheel wells with the right adapters too. I hear people saying they won't cause they've got 255/60 or 265/60 tires that rub. What they fail to realize is those tires are MUCH taller then 275/40R17 tires. When you have a 27-28 inch tire, you're going to have problems when the wheel wells were only sized to hold a 26 inch tire. The height causes more problems then the width.

 

Here is a great tire calculator site, I use it all the time.
http://www.dakota-truck.net/TIRECALC/tirecalc.html

------------------
92 Camaro RS 5.0 5-Speed (Quasar Blue)
T-Tops
14" Open Air Cleaner
3.08 Posi-trac
Edelbrock TBI Intake
Crane cam
Ported & polished stock heads 3 angle valve job
HyperTech Chip
SLP Headers (Ceramic Coated)
UltraFlo cat-back exhaust

74 Dodge Dart Sport 360 (11.2 1/4 mile)

2000 Dodge 1500 Ram Sport

 

thanks raskel & dart, the info is "right on the money honey".
i've tried dart's site with the convertor and the tire of choice for me will be...235/60R15 wich is exactly what one of our boys told me few lines above.
and the error margin will be really close to 0.
thanks again to all of you for the help
CAMAROS FOREVER MAN...
fernando.

------------------
third gen muscle power is the only thing that can match the power of flight...