Tire size and Speedo error calculator

Rtech · 7th December 2005, 13:50

This is useful for anyone looking at upsizing their wheel and tyres. What's different about this calculator is that it also show you you speedo error after the change.

The basic rule in upsizing is that you want to keep you overall diameter the same as the OE tyre.

Link: http://www.miata.net/garage/tirecalc.html

speedsatya · 7th December 2005, 14:00

http://www.carbibles.com/tyre_bible.html

this also will help

kpzen · 7th December 2005, 23:16

these links are of great help for tyre upsizing...
Can anyone please enlighten on pros n cons of having different rim sizes while going for a tyre upsize...??

KP

Rtech · 8th December 2005, 09:51

kpzen, read through the link Satya has posted. It will tell you everything you need to know about tyre upsizing. It goes into great detail there, but if you still have some questions, post them.

speedsatya · 8th December 2005, 11:04

keeping same OD ,smaller rim means higher aspect ratio or higher profile ...so this will give good ride quality but poor handling...
on the other hand bigger rim size means lower profile ...so this means harsh ride quality over bad roads ...but better handling when compared to the higher profile tires...

kpzen · 8th December 2005, 15:12

hey rtech

By different rim sizes...I meant having upsized tyres with different rim width size..
For eg. If we upsize the tyre of zen from stock 145/80-12 to 165/65-13...and use 13x 4j rims...wat are the disadvantages of this combination..?

KP

Rtech · 8th December 2005, 15:18

As per the rim width calculator (check Satya's link again) you should use:

145/80/12: 4-5.5 J
165/65/13: 4.5-6 J

The upsize seems to be within limits though.

The disadvantge is that you are now running a lowr profile, so your ride will be way more harsh on a small car like the Zen.

kpzen · 9th December 2005, 22:09

hey Rtech

I agree low profile tyres will give you a harsh ride.....
But... I'm facing a different problem with rim width size...
I upgraded my zen tyres to 165/65-13 with stock steel 13x 4j rims....I know the width of rim isn't correct as per rim size calculator...
My handling n braking become pathetic....and driving at high speeds have become scary to say the least...
I just want to know the how a wrong size rim affects the running of a car...??
Will it have any affect on any other parts like suspension and of course tyres..

KP

angelfire · 8th January 2006, 16:56

awesome link satya!!...hey guys..please check out the links...its got everythin you want know about tires..upsizin..etc..

nitrous · 27th January 2006, 02:24

Whats the max difference(%) to be kept in mind while choosing an upsize?
Is it 2%??

v1p3r · 27th January 2006, 03:40

http://www.1010tires.com/TireSizeCalculator.asp

This site also gives you a warning if your OD changes by 3% or over, which is the limit, according to them.

nitrous · 24th February 2006, 12:55

Can the difference also be in the negative (-3)%??

~~VinZ~~ · 20th March 2006, 14:09

These links provided are of great for ppl to know about upsizing the tyres

thanks guys....

Jay · 26th March 2006, 10:59

hey Rtech and Speedsatya, thanks for the links dudes.... until i saw these links i wasnt sure of the differences.... helping me a lot now....

princesri1981 · 5th April 2006, 22:35

Quote:

Originally Posted by v1p3r

http://www.1010tires.com/TireSizeCalculator.asp

This site also gives you a warning if your OD changes by 3% or over, which is the limit, according to them.

Ya the link is really helpful

7th December 2005, 13:50	#1
Rtech Team-BHP Support Join Date: Apr 2004 Location: Bombay Posts: 5,770 Thanked: 359 Times View My Garage	Tire size and Speedo error calculator This is useful for anyone looking at upsizing their wheel and tyres. What's different about this calculator is that it also show you you speedo error after the change. The basic rule in upsizing is that you want to keep you overall diameter the same as the OE tyre. Link: http://www.miata.net/garage/tirecalc.html
	(1) Thanks

7th December 2005, 14:00	#2
speedsatya Senior - BHPian Join Date: May 2004 Location: bangalore/manga Posts: 3,169 Thanked: 738 Times View My Garage	http://www.carbibles.com/tyre_bible.html this also will help
	(1) Thanks

7th December 2005, 23:16	#3
kpzen Senior - BHPian Join Date: Oct 2004 Location: Faridabad Posts: 5,610 Thanked: 1,876 Times View My Garage	these links are of great help for tyre upsizing... Can anyone please enlighten on pros n cons of having different rim sizes while going for a tyre upsize...?? KP
	() Thanks

8th December 2005, 09:51	#4
Rtech Team-BHP Support Join Date: Apr 2004 Location: Bombay Posts: 5,770 Thanked: 359 Times View My Garage	kpzen, read through the link Satya has posted. It will tell you everything you need to know about tyre upsizing. It goes into great detail there, but if you still have some questions, post them.
	() Thanks

8th December 2005, 11:04	#5
speedsatya Senior - BHPian Join Date: May 2004 Location: bangalore/manga Posts: 3,169 Thanked: 738 Times View My Garage	keeping same OD ,smaller rim means higher aspect ratio or higher profile ...so this will give good ride quality but poor handling... on the other hand bigger rim size means lower profile ...so this means harsh ride quality over bad roads ...but better handling when compared to the higher profile tires...
	() Thanks

8th December 2005, 15:12	#6
kpzen Senior - BHPian Join Date: Oct 2004 Location: Faridabad Posts: 5,610 Thanked: 1,876 Times View My Garage	hey rtech By different rim sizes...I meant having upsized tyres with different rim width size.. For eg. If we upsize the tyre of zen from stock 145/80-12 to 165/65-13...and use 13x 4j rims...wat are the disadvantages of this combination..? KP
	() Thanks

8th December 2005, 15:18	#7
Rtech Team-BHP Support Join Date: Apr 2004 Location: Bombay Posts: 5,770 Thanked: 359 Times View My Garage	As per the rim width calculator (check Satya's link again) you should use: 145/80/12: 4-5.5 J 165/65/13: 4.5-6 J The upsize seems to be within limits though. The disadvantge is that you are now running a lowr profile, so your ride will be way more harsh on a small car like the Zen. Last edited by Rtech : 8th December 2005 at 15:20.
	() Thanks

9th December 2005, 22:09	#8
kpzen Senior - BHPian Join Date: Oct 2004 Location: Faridabad Posts: 5,610 Thanked: 1,876 Times View My Garage	hey Rtech I agree low profile tyres will give you a harsh ride..... But... I'm facing a different problem with rim width size... I upgraded my zen tyres to 165/65-13 with stock steel 13x 4j rims....I know the width of rim isn't correct as per rim size calculator... My handling n braking become pathetic....and driving at high speeds have become scary to say the least... I just want to know the how a wrong size rim affects the running of a car...?? Will it have any affect on any other parts like suspension and of course tyres.. KP
	() Thanks

8th January 2006, 16:56	#9
angelfire BHPian Join Date: Sep 2005 Location: Mangalore/Chicago Posts: 251 Thanked: Once View My Garage	awesome link satya!!...hey guys..please check out the links...its got everythin you want know about tires..upsizin..etc.. Last edited by angelfire : 8th January 2006 at 16:58.
	() Thanks

27th January 2006, 02:24	#10
nitrous Senior - BHPian Join Date: May 2004 Location: UAE/Lon/Madras Posts: 6,965 Thanked: 325 Times View My Garage	Whats the max difference(%) to be kept in mind while choosing an upsize? Is it 2%??
	() Thanks

27th January 2006, 03:40	#11
v1p3r Senior - BHPian Join Date: Feb 2005 Location: BLR / DXB / LON Posts: 5,334 Thanked: 6,896 Times View My Garage	http://www.1010tires.com/TireSizeCalculator.asp This site also gives you a warning if your OD changes by 3% or over, which is the limit, according to them.
	() Thanks

24th February 2006, 12:55	#12
nitrous Senior - BHPian Join Date: May 2004 Location: UAE/Lon/Madras Posts: 6,965 Thanked: 325 Times View My Garage	Can the difference also be in the negative (-3)%??
	() Thanks

20th March 2006, 14:09	#13
~~VinZ~~ BHPian Join Date: Mar 2006 Location: Bangalore Posts: 288 Thanked: 7 Times View My Garage	These links provided are of great for ppl to know about upsizing the tyres thanks guys....
	() Thanks

26th March 2006, 10:59	#14
Jay BHPian Join Date: Mar 2006 Location: Bangalore Posts: 819 Thanked: 8 Times	hey Rtech and Speedsatya, thanks for the links dudes.... until i saw these links i wasnt sure of the differences.... helping me a lot now....
	() Thanks