Tire Specs, Need HELP
Thread Starter
Heel & Toe
Joined: Sep 2003
Posts: 17
Likes: 0
From: Virginia Beach Virginia
Tire Specs, Need HELP
I am looking to put on a set of stock 1999 wheels on my 1987 convertible. I know the wheels have clearance and space cprrectly, but I need some help with tire sizing. Will the factory 245/45/17's have the same diamter as the 255/50/16s? Im trying to keep the diameters for the front and rear as close to the 87 specs as possible. Any and all help is welcomed!
Thanks all
Scott
Thanks all
Scott
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Tire Specs, Need HELP (Privette87)
check http://www.tirerack.com
they have a computer that will help you keep the tires straight....
There are formulas for getting to tire height:
For example... the 245/45/17's would be like this:
245 (tread width in mm) x .45 (aspect ratio) = 11 centimeters for the sidewall height, which is about 4.3125" high.
then, 4.3125 x 2 = 8.625 + 17 = 25.625 x 3.14159 = 80.50" circumference.
now... the 255/50/16s would be:
255 x 50 = 127.5mm = 12.75 cm = 5" x 2 = 10" + 16 = 26 x 3.14159 = 81.7" circumference
That is well within tolerances!
the 2 numbers that matter most are the height and the circumference. they are sooo close, no one would care.
they have a computer that will help you keep the tires straight....
There are formulas for getting to tire height:
For example... the 245/45/17's would be like this:
245 (tread width in mm) x .45 (aspect ratio) = 11 centimeters for the sidewall height, which is about 4.3125" high.
then, 4.3125 x 2 = 8.625 + 17 = 25.625 x 3.14159 = 80.50" circumference.
now... the 255/50/16s would be:
255 x 50 = 127.5mm = 12.75 cm = 5" x 2 = 10" + 16 = 26 x 3.14159 = 81.7" circumference
That is well within tolerances!
the 2 numbers that matter most are the height and the circumference. they are sooo close, no one would care.
Le Mans Master
Joined: May 2003
Posts: 5,362
Likes: 3
From: Delray Beach FL
Re: Tire Specs, Need HELP (Privette87)
I checked out BF Goodrich's site for you. (www.bfgoodrich.com) They have a lot of usefull info on their tires in regards to your question. Here is what I found:
245/45/17 Revs/Mile at 45 mph: 811
255/45/17 Revs/Mile at 45 mph: 798
255/50/16 Revs/Mile at 45 mph: 797
245/50/16 Revs/Mile at 45 mph: 809
So, if factory is 255/50/16, I would go with 255/45/17's. You would be just about dead on.
:cheers:
245/45/17 Revs/Mile at 45 mph: 811
255/45/17 Revs/Mile at 45 mph: 798
255/50/16 Revs/Mile at 45 mph: 797
245/50/16 Revs/Mile at 45 mph: 809
So, if factory is 255/50/16, I would go with 255/45/17's. You would be just about dead on.
:cheers:
Thread Starter
Heel & Toe
Joined: Sep 2003
Posts: 17
Likes: 0
From: Virginia Beach Virginia
Re: Tire Specs, Need HELP (Whitvette)
I can't thank you guys enough! I really do appreciate the help, mathematically those 255/45/17's seem to be a dead match. I'm really thankful for the help and I am glad to be a part of the corvette scene now :chevy
Thread Starter
Heel & Toe
Joined: Sep 2003
Posts: 17
Likes: 0
From: Virginia Beach Virginia
Re: Tire Specs, Need HELP (Whitvette)
It seems Im going to need a little more help in my tire purchase afterall. I called Tirerack and spoke with one of their reps. They claim that a 245/45 or a 255/45 will not have the load capacity although the diameters are within tolerance. The tire size they say is needed for an 87 load capacity on a 17 is a 270/40! Will this even fit on the 99 17" wheel? will I need spacers to run this tire on the front of my 87?
I never thought switching wheels would have so much work entailed! But it needs to happen as I have a C5 brake upgrade kit sitting in the garage... it calls to me! Thanks for the help , this newbie appreciates it!
Scott
I never thought switching wheels would have so much work entailed! But it needs to happen as I have a C5 brake upgrade kit sitting in the garage... it calls to me! Thanks for the help , this newbie appreciates it!
Scott
Le Mans Master
Joined: May 2003
Posts: 5,362
Likes: 3
From: Delray Beach FL
Re: Tire Specs, Need HELP (Privette87)
Here is what I got from BF Goodrich:
Tire Size Max Load (lbs@psi)
245/45/17 1521@44
255/45/17 1653@44
255/50/16 1687@44
245/50/16 1609@44
I went from 1764 to 1521 on my tires and have yet to have a problem. Looking at BFG's specs, the difference of 34 lbs per axle isn't that bad. Besides, I was running 255/45/17's on my Vette before I went to 18" rims. They were factory in 93. As for spacers, I am not sure. AFS does sell rims for the 84-87 Vettes that don't need spacers. If you get 88+ rims, you may need spacers.
:cheers:
Tire Size Max Load (lbs@psi)
245/45/17 1521@44
255/45/17 1653@44
255/50/16 1687@44
245/50/16 1609@44
I went from 1764 to 1521 on my tires and have yet to have a problem. Looking at BFG's specs, the difference of 34 lbs per axle isn't that bad. Besides, I was running 255/45/17's on my Vette before I went to 18" rims. They were factory in 93. As for spacers, I am not sure. AFS does sell rims for the 84-87 Vettes that don't need spacers. If you get 88+ rims, you may need spacers.
:cheers:
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