RE: [Chevelle-List] Rear Tire Size

[396guy]

I don't think it's inversely related.  The effective section height is directly related to whatever aspect ratio tire is chosen - regardless of the section width.  One has nothing to do with the other UNTIL they're combined.  That is, a 275mm section width can come in a 35, 40, 45, 50, etc aspect ratio thereby determining the section height.   The second part of your question leaves out too many variables.  What were the ORIGINAL gears in the rear and does the TH400 have the correct speedo gear for the original rear and/or the 3.55's?  Then you have to know the exact 15" tire diameter and the exact 17" tire diameter.   http://www.miata.net/garage/tirecalc.html will calculate the difference in your speedo between two tire sizes - assuming the starting tire (a 15" in this case) is causing the speedo to read accurately.   Dale      -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Mabs, Kenneth Sent: Friday, February 22, 2002 9:06 AM To: '[EMAIL PROTECTED]' Subject: RE: [Chevelle-List] Rear Tire Size sorry i didnt know the section height was inversely related to the section width.  when using 3.55's and a th400  about how many rpm's would you drop if switching from a 15 in tire to a 17 in? -----Original Message----- From: Herbert Lumpp [mailto:[EMAIL PROTECTED]] Sent: Friday, February 22, 2002 12:59 PM To: [EMAIL PROTECTED] Subject: Re: [Chevelle-List] Rear Tire Size The reason a 60 will clear better than a 50 is because when you go with a 60 the widest tire available is a 275, where with a 50 you can go to a 295.  The narrower, but taller tire will give more fender clearance.  This will also affect the final drive ratio - something else to consider when drastically changing tire sizes.   If you follow this link, there is a tire height calculator along with some other good info...   http://www.ring-pinion.com/calc-tire.html   cYa-   Herb ----- Original Message ----- From: Mabs, Kenneth To: '[EMAIL PROTECTED]' Sent: Friday, February 22, 2002 6:45 AM Subject: RE: [Chevelle-List] Rear Tire Size if you went with 60's instead of the 50's you have now wouldn't that just increase the size of your sidewall?  how would this help from damaging your quarter panel? -----Original Message----- From: Craig & Cerena Robertson [mailto:[EMAIL PROTECTED]] Sent: Friday, February 22, 2002 6:41 AM To: [EMAIL PROTECTED] Subject: Re: [Chevelle-List] Rear Tire Size My SS came with P295/50/R15.  I think that they will possible rub and damage the quarter panel if I hit a pot hole.  I'm going to try and sell them and replace with 60's.  They look great on the car but I don't want to damage anything.   Craig ----- Original Message ----- From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, February 22, 2002 12:25 AM Subject: Re: [Chevelle-List] Rear Tire Size I am running 275 60 15's on my 70 with 4.10 gears, 75 mph is 3500 RPM's.  Funny thing is it gets 15 mpg on highway with the 4.10's and a 500 HP 454. Tom