Gauge / rims question
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From: Smithfield RI
Car: Hardtop 84' z/95' Cheyenne
Engine: 305 H.O./4.3L
Transmission: 5-speed manual/Auto
Gauge / rims question
Ok i have 14s on my car now and i was going to go with some 15 inch rims, will this affect my speedo? If it does i have the cluster out of an 82 T/a that has 15 inch rims can i just put that cluster in there and it will work?
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From: St.Louis, Missouri
Car: 91 Camaro RS
Engine: 3.1L V-6
Transmission: Fresh 700R4
It's all in the overall diameter of the tire the size of the rims dosen't matter use www.tirerack.com i belive they have a calculater that will figure up overall diameter just use it to find the diameter of your 14's then chose some 15's in the same size
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From: Smithfield RI
Car: Hardtop 84' z/95' Cheyenne
Engine: 305 H.O./4.3L
Transmission: 5-speed manual/Auto
the rims are 15 inch "snowflake" rims that i wanna put on i just wanted a normal size sidewall nothing like those rubber band type 40 tires How off would the speedo be? like a noticable amount?
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From: St.Louis, Missouri
Car: 91 Camaro RS
Engine: 3.1L V-6
Transmission: Fresh 700R4
it shouldn't be off much if you use a factory size tire maybe 2-3 mph max just remember that the speedo will read slightly slower than you are going
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From: Halifax, NS,Canada
Car: 1995 Z28
Engine: LT1
Transmission: Built 4L60E
Axle/Gears: 3.23's - Limited Slip
The stock size for my firebird was 215/65R15
That is about 26 in. diameter.
So as long as the tires you place on your 15's are in that range, your speedo should not be affected. 235/60R15 is another size that does not affect the speedo.
I am not sure on the 14 inch tire size. What are the #'s on your tires now, and what does it say on the door for recommended tires? This could be an important piece of info.
That is about 26 in. diameter.
So as long as the tires you place on your 15's are in that range, your speedo should not be affected. 235/60R15 is another size that does not affect the speedo.
I am not sure on the 14 inch tire size. What are the #'s on your tires now, and what does it say on the door for recommended tires? This could be an important piece of info.
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From: Lehigh Valley, PA
Car: 00 T/A Firehawk
Engine: 346ci LS1
Transmission: MN6
Axle/Gears: 3.42 LSD
I went from the 15" concave style rims on my car to the 16" 1991-1992 Z28 Rims and they were essentially the same height. The 15" wheels had a taller sidewall and the 16" rims had a smaller sidewall thus making up for the difference between rim sizes. Thus speedo is still correct to my knowledge.
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From: Central NJ, USA
Car: 1986 Firebird
Engine: 2.8 V6
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Skatepunk, for concrete answers, get out a calculator:
And more info: http://www.offroaders.com/info/tech-...ng/mph-rpm.htm
Let us know what you come up with. Work up your numbers for your current size tires, then work up a set of numbers for each of your wish-list tire sizes.
Originally posted by TomP
Oh, er, yeah, say you like your tires now, but you want them a bit wider. Just do some conversions... grab tire sizes, and do the following easy calculations. I'll use my original front tire, P215/65r15, as the example.
P215/65r15
P=passenger
215= section width
65=aspect ratio, "percentage"
15=rim size
215 divided by 25 = converts to inches = 8.6 = tread width
8.6 times 0.65 = sidewall height = 5.59 inches
For tire height, remember, you have two sidewalls (top and bottom), and a rim in the middle. So multiply the sidewall height by two, and add the rim size:
5.59 + 5.59 + 15 = 26.18 inch tire height
Now, these are all approximates, two tires, same size stamping, by different makers, can be slightly different sizes due to different manufacturing methods. But, they're close enough. So I wanted a front tire that was a bit wider, but the same size. There's more complicated ways of doing this, but I just took the next wider tire, and ran some calcluations on it, and it worked:
P225/60r15: 225/25 = 9.0 inches wide. 9 times 0.60 = 5.4 sidewall. Tire height = 25.8 inches.
So I wound up with a tire that was a bit wider, and a bit shorter. This is also good because you can use your existing tire as a beginning point. Say you want to run a P235/60 on the front, but you're not sure it'll fit. Run the calculations, you get a tire that's 9.4 inches wide and 26.28 inches tall. Your current tire is a P215/65r15, 8.6 inches wide, 26.18 inches tall. The height is negligable, maybe 1/8 to 1/4 inch difference. But, the tire is now almost an inch wider! So measure a half inch "extra" from the inside and outside of each tire; see if it'll fit. Got what I mean?
Remember too- a tire too drastic in height change will affect your speedometer. Taller tire = speedometer reads "slow" (you're doing 68 but your speedo says 55), and that's asking for a speeding ticket! Shorter tire = speedometer reads fast (you're doing 50 but your speedo says 60). So try to stick with tires that are close to the same size.
Also, if you put a very wide tire on a thin rim, the sidewall won't look flat, it'll look "bubbly". My P255/70r15's fit on my original 15x7 rims, but the sidewalls looked very round... when I changed the rear rims to 15x8, the sidewalls flattened out.
A wider tire will hydroplane easier, get less traction on snow, and your car will like to "wander" on the highway. Know those grooves caused by small car tires? Well your wide tires will want to be half-in and half-out, and on an old highway, you might be fighting the steering wheel every now and then.
One last thing; remember that our front tires like to rub the inner wheel well on sharp turns... keep that in mind when going to a wider tire. A good idea might be to stick with "optional" tire sizes for f-bodies... for instance, my p225/60r15's on the car now were an optional tire size. I think the P235/60r15's were, too... but don't quote me.
When in doubt, check with your tire shop...
Oh, er, yeah, say you like your tires now, but you want them a bit wider. Just do some conversions... grab tire sizes, and do the following easy calculations. I'll use my original front tire, P215/65r15, as the example.
P215/65r15
P=passenger
215= section width
65=aspect ratio, "percentage"
15=rim size
215 divided by 25 = converts to inches = 8.6 = tread width
8.6 times 0.65 = sidewall height = 5.59 inches
For tire height, remember, you have two sidewalls (top and bottom), and a rim in the middle. So multiply the sidewall height by two, and add the rim size:
5.59 + 5.59 + 15 = 26.18 inch tire height
Now, these are all approximates, two tires, same size stamping, by different makers, can be slightly different sizes due to different manufacturing methods. But, they're close enough. So I wanted a front tire that was a bit wider, but the same size. There's more complicated ways of doing this, but I just took the next wider tire, and ran some calcluations on it, and it worked:
P225/60r15: 225/25 = 9.0 inches wide. 9 times 0.60 = 5.4 sidewall. Tire height = 25.8 inches.
So I wound up with a tire that was a bit wider, and a bit shorter. This is also good because you can use your existing tire as a beginning point. Say you want to run a P235/60 on the front, but you're not sure it'll fit. Run the calculations, you get a tire that's 9.4 inches wide and 26.28 inches tall. Your current tire is a P215/65r15, 8.6 inches wide, 26.18 inches tall. The height is negligable, maybe 1/8 to 1/4 inch difference. But, the tire is now almost an inch wider! So measure a half inch "extra" from the inside and outside of each tire; see if it'll fit. Got what I mean?
Remember too- a tire too drastic in height change will affect your speedometer. Taller tire = speedometer reads "slow" (you're doing 68 but your speedo says 55), and that's asking for a speeding ticket! Shorter tire = speedometer reads fast (you're doing 50 but your speedo says 60). So try to stick with tires that are close to the same size.
Also, if you put a very wide tire on a thin rim, the sidewall won't look flat, it'll look "bubbly". My P255/70r15's fit on my original 15x7 rims, but the sidewalls looked very round... when I changed the rear rims to 15x8, the sidewalls flattened out.
A wider tire will hydroplane easier, get less traction on snow, and your car will like to "wander" on the highway. Know those grooves caused by small car tires? Well your wide tires will want to be half-in and half-out, and on an old highway, you might be fighting the steering wheel every now and then.
One last thing; remember that our front tires like to rub the inner wheel well on sharp turns... keep that in mind when going to a wider tire. A good idea might be to stick with "optional" tire sizes for f-bodies... for instance, my p225/60r15's on the car now were an optional tire size. I think the P235/60r15's were, too... but don't quote me.
When in doubt, check with your tire shop...
Let us know what you come up with. Work up your numbers for your current size tires, then work up a set of numbers for each of your wish-list tire sizes.
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