Please Explain tire size difference. - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Scott@Bjorn3D · 07-01-2009, 01:22 PM

What the difference 275/40/20 and 275/45/20

Thanks!!

Mr_Draco · 07-01-2009, 01:32 PM

Quote:

Originally Posted by Scott@Bjorn3D

What the difference 275/40/20 and 275/45/20

Thanks!!

The 40 and the 45 are the height if the sidewall. They are measured in millimeters but the 40 is a percentage of the width of the tire (275), not the actual measurement. The increase from a 275/40 to a 275/45 is quite substantial.

Scott@Bjorn3D · 07-01-2009, 01:33 PM

Ok so putting a 275/45/20 will mess up the odometor then right?

speedster · 07-01-2009, 01:34 PM

Quote:

Originally Posted by Mr_Draco

The 40 and the 45 are the height if the sidewall. They are measured in millimeters but the 40 is a percentage of the width of the tire (275), not the actual measurement.

Draco has it. 40 / 45 is the Tire Aspect Ratio. % of height relative to width.

speedster · 07-01-2009, 01:37 PM

Ok so putting a 275/45/20 will mess up the odometor then right?

It could change it by as much as 12.5%. Electronic speedos can be re-calibrated. Don't know the method on these new LS3/L99 computers. Maybe Andy at ADM Performance could help you since they put 315's on a car, but then again 315/35 height = 275/40 height. Maybe ask Hennessey too.

Mr_Draco · 07-01-2009, 01:37 PM

Quote:

Originally Posted by Scott@Bjorn3D

Ok so putting a 275/45/20 will mess up the odometor then right?

Yes. The change of the speedometer is a directly proportional to change in circumference of the tire. If you increase the circumference of the tire by say 10% then the speedometer will read 10% under what you really are doing. Like if your speedometer says 70 mph you are really doing 77 mph.

You can get the speedometer recalibrated for the larger tires if you want though.

Scott@Bjorn3D · 07-01-2009, 01:42 PM

Well hopefully Goodyear will come out with the these in the right size: http://www.tirerack.com/tires/tires....e1=yes&place=0

DanD · 07-01-2009, 01:59 PM

28.6 stock height, 29.7 for the 45's... I bet 3-4 mph faster at 60mph.. prob. never notice anything IMO..

easy way to figure height is 275x40%/25.4x2+20=28.66 of course all brands of tires can vary about 1/2" either way..

Rob@WretchedMS · 07-01-2009, 02:11 PM

Quote:

Originally Posted by Scott@Bjorn3D

Well hopefully Goodyear will come out with the these in the right size: http://www.tirerack.com/tires/tires....e1=yes&place=0

Those are good tires, I'm hoping the Bridgestone will release the Potenza RE-11's in the Camaro Sizes.

TheNetGarage · 07-01-2009, 02:15 PM

Quote:

Originally Posted by Scott@Bjorn3D

Well hopefully Goodyear will come out with the these in the right size: http://www.tirerack.com/tires/tires....e1=yes&place=0

Hey Scott,

I will vouche for those GS-D3's. The absolute BEST wet traction BAR NONE. ANd really good traction on dry in warm weather. Under 40 degrees they break loose easy and squeel on corners. Not a cold weather tire, STRICTLY summer.

*radz28* · 07-01-2009, 02:58 PM

Quote:

Originally Posted by TheNetGarage

Hey Scott,

I will vouche for those GS-D3's. The absolute BEST wet traction BAR NONE. ANd really good traction on dry in warm weather. Under 40 degrees they break loose easy and squeel on corners. Not a cold weather tire, STRICTLY summer.

While I can't comment directly on these, my brother had these 315s on his '02 Z28 and loved them. He beat the piss out of them and they lasted way longer than we expected. They gripped like velcro and were really good in the rain. Like 'Garage said though: the cold weather was a little different. If they had sizes I'd be looking for, those are tires I'd definately have a serious look at.

Xanthos · 07-01-2009, 04:53 PM

Bah, you think you guys have it bad? I realized the other day that in order to get the tire width I want with the wheels I want and keep the stock 28.6 inch diameter, I need a 275/50/18.

Not going to happen... I think I'll just have to settle for something slightly smaller and just get the speedo recalibrated. Maybe a 27 inch total diameter.
- X

MyNewSolstice · 07-01-2009, 05:23 PM

yes it will be off but with analog gauges it already is! about 1-3 mph lag

DarricSS · 07-01-2009, 05:27 PM

Here is a good Tire calcultor, used this allot trying to figure out what the maximum tire my truck would fit.

And you can put in 2 tire sizes to see what the differnce will be.

http://www.discounttire.com/dtcs/infoTireMath.dos

And here is a pretty good explanation for what the tire sidewall means.

http://www.discounttire.com/dtcs/infoSidewall.dos

07-01-2009, 01:22 PM	#1
Scott@Bjorn3D Drives: Kami, 2013 2SS LS3 Luvin Join Date: Oct 2008 Location: Eufaula, Alabama Posts: 6,427	Please Explain tire size difference. What the difference 275/40/20 and 275/45/20 Thanks!!

07-01-2009, 01:37 PM	#5
speedster SST... Drives: SST Camaro 2010 Join Date: Oct 2008 Location: East Coast of Florida Posts: 5,927 View My Garage	Ok so putting a 275/45/20 will mess up the odometor then right? It could change it by as much as 12.5%. Electronic speedos can be re-calibrated. Don't know the method on these new LS3/L99 computers. Maybe Andy at ADM Performance could help you since they put 315's on a car, but then again 315/35 height = 275/40 height. Maybe ask Hennessey too. __________________

07-01-2009, 01:59 PM	#8
DanD Drives: 6 camaros Join Date: Feb 2009 Location: ma Posts: 320	28.6 stock height, 29.7 for the 45's... I bet 3-4 mph faster at 60mph.. prob. never notice anything IMO.. easy way to figure height is 275x40%/25.4x2+20=28.66 of course all brands of tires can vary about 1/2" either way.. __________________ 2010 IOM RS/SS TVS2300, cam, stall, headers 2002 Z28 427 2002 SSLE Convertible 1968 383 Camaro 1968 327 Camaro Convertible 1967 RS 327 1967 Pro-Tour LS3 in progress

07-01-2009, 04:53 PM	#12
Xanthos PWA Relapse Drives: Formerly-Stick Join Date: Mar 2008 Location: Oklahoma Posts: 12,588 View My Garage	Bah, you think you guys have it bad? I realized the other day that in order to get the tire width I want with the wheels I want and keep the stock 28.6 inch diameter, I need a 275/50/18. Not going to happen... I think I'll just have to settle for something slightly smaller and just get the speedo recalibrated. Maybe a 27 inch total diameter. - X __________________ 2017 1LT/RS A8 Hyper Blue Metallic

07-01-2009, 05:27 PM	#14
DarricSS Drives: '10 Camaro SS Join Date: Apr 2009 Location: Gilbert, Arizona Posts: 1,047	Here is a good Tire calcultor, used this allot trying to figure out what the maximum tire my truck would fit. And you can put in 2 tire sizes to see what the differnce will be. http://www.discounttire.com/dtcs/infoTireMath.dos And here is a pretty good explanation for what the tire sidewall means. http://www.discounttire.com/dtcs/infoSidewall.dos __________________ 2010, SIM, 2SS/RS, LS3, CGM Stripes

07-01-2009, 01:33 PM	#3
Scott@Bjorn3D Drives: Kami, 2013 2SS LS3 Luvin Join Date: Oct 2008 Location: Eufaula, Alabama Posts: 6,427	Ok so putting a 275/45/20 will mess up the odometor then right?

07-01-2009, 01:42 PM	#7
Scott@Bjorn3D Drives: Kami, 2013 2SS LS3 Luvin Join Date: Oct 2008 Location: Eufaula, Alabama Posts: 6,427	Well hopefully Goodyear will come out with the these in the right size: http://www.tirerack.com/tires/tires....e1=yes&place=0

07-01-2009, 05:23 PM	#13
MyNewSolstice Drives: 06 Solstice Join Date: Apr 2009 Location: Pittsburgh Posts: 349 View My Garage	yes it will be off but with analog gauges it already is! about 1-3 mph lag

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