Tire size numbers ?
Thread Starter
Le Mans Master
Joined: Feb 2004
Posts: 8,629
Likes: 16
From: York PA
Tire size numbers ?
295/35/18 The middle number is the height of the tire ?
How much difference is their between 30 & 40 height ?
Would it change your gearing ?
If so, why not have say 4.10 rear gears for the track with lower tires and higher tires for the street for cruising?
How much difference is their between 30 & 40 height ?
Would it change your gearing ?
If so, why not have say 4.10 rear gears for the track with lower tires and higher tires for the street for cruising?
Race Director
Joined: May 2000
Posts: 14,542
Likes: 5
Re: Tire size numbers ? (4DRUSH)
Here you go:
http://www.tirerack.com/tires/tiretech/
and
http://www.miata.net/garage/tirecalc.html
All the answers. :smash:
http://www.tirerack.com/tires/tiretech/
and
http://www.miata.net/garage/tirecalc.html
All the answers. :smash:
Melting Slicks
Joined: Aug 2003
Posts: 2,006
Likes: 1,338
From: Des Plaines, Il
Re: Tire size numbers ? (4DRUSH)
The Middle number is the aspect ratio. Its the height of the tire in relation to its width. (so a 205/40/17 would be less tall than a 275/40/17)
No reason you cant run larger or smaller tires. It will effect your gearing, but also effect your speedo accuracy.
No reason you cant run larger or smaller tires. It will effect your gearing, but also effect your speedo accuracy.
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Re: Tire size numbers ? (4DRUSH)
The middle number (aspect ratio) is expressed as a percentage of the tire's width. So, as a tire gets wider, it also gets taller if it's the same aspect ratio.
For example, a 335/30/18 is a taller tire than a 265/35/18 even though the aspect ratio is less. 30% of 335 happens to be more than 35% of 265.
So, there is no exact height dimension difference unless you specify the tire's width as well.
:cheers:
For example, a 335/30/18 is a taller tire than a 265/35/18 even though the aspect ratio is less. 30% of 335 happens to be more than 35% of 265.
So, there is no exact height dimension difference unless you specify the tire's width as well.
:cheers:
Melting Slicks
Joined: Sep 2003
Posts: 2,458
Likes: 105
From: Northville Michigan
Re: Tire size numbers ? (4DRUSH)
Jay,
The first number is the width of the tread in mm. The second number is the Aspect ratio, which is a percent of the tread width. These should be followed by the speed rating letter - Z - as an example, followed by the type of construction - R - for radial, next will come the rim diameter in inches - 18. These can be followed by another letter - Y - for example, which designates if it has a speed rating greater than Z.
Here is a formula for calculating the diameter of the tire on its rim:
(Width x Aspect Ratio x 2 x 0.03937) + rim diameter = Tire-Wheel Assembly Diameter
For your 296/35ZR18 tire wheel assembly here is the calculation:
(295 x .35 x 2 x 0.03937) + 18 = 26.129 inches
Good luck :seeya
The first number is the width of the tread in mm. The second number is the Aspect ratio, which is a percent of the tread width. These should be followed by the speed rating letter - Z - as an example, followed by the type of construction - R - for radial, next will come the rim diameter in inches - 18. These can be followed by another letter - Y - for example, which designates if it has a speed rating greater than Z.
Here is a formula for calculating the diameter of the tire on its rim:
(Width x Aspect Ratio x 2 x 0.03937) + rim diameter = Tire-Wheel Assembly Diameter
For your 296/35ZR18 tire wheel assembly here is the calculation:
(295 x .35 x 2 x 0.03937) + 18 = 26.129 inches
Good luck :seeya
