Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Jun 2011

Nitrogen Inflation for Passenger Car and Light Truck Tires

Page Range: 125 – 160
DOI: 10.2346/1.3593787
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Abstract

Nitrogen as an inflation gas for passenger car and light truck tires use is widely available commercially. Consumers are confronted with a bewildering selection of offerings, and suppliers tout the purity of their nitrogen generation systems and effectiveness of using the gas in place of air. This paper develops models for the initial tire nitrogen purity, the inflation pressure loss rate, and the evolution of the nitrogen gas purity in the tire as a function of the gas used to top off the tire over its life. A series of simulations using the basic model is developed for air and various purities of nitrogen initial inflation with monthly top-off using air or various purities of nitrogen. The initial inflation pressure loss rate is shown as a function of the tire’s initial nitrogen purity. This paper proposes the use of the total oxygen passing through the tire over its lifetime as a metric for evaluation of various inflation schemes. This metric is developed for several of the popular available nitrogen inflation purities using both air and nitrogen as a top-off gas.

Keywords: nitrogen inflation; inflation pressure loss rate; nitrogen purity evolution; oxygen flow across a tire
Copyright: The Tire Society
FIG. 1
FIG. 1

Tire nitrogen purity for equilibrium oxygen.

FIG. 2
FIG. 2

Oxygen partial pressure as a function of tire maximum pressure and nitrogen purity.

FIG. 3
FIG. 3

Inflation purity evolution for inflation gas of 95% nitrogen purity.

FIG. 4
FIG. 4

Inflation purity evolution for inflation gas of 98% nitrogen purity.

FIG. 5
FIG. 5

Nitrogen purity evolution by inflation step for standard load passenger car tires.

FIG. 6
FIG. 6

Nitrogen purity evolution by inflation step for LRE light truck tires.

FIG. 7
FIG. 7

Gas purity evolution over service life for P235/75R15 SL tire inflated with air and topped off with air.

FIG. 8
FIG. 8

Partial pressure evolution over service life for P235/75R15 SL tire inflated with air and topped off with air.

FIG. 9
FIG. 9

Oxygen permeation over service life for P235/75R15 SL tire inflated with air and topped off with air.

FIG. 10
FIG. 10

Partial pressure evolution over service life for P235/75R15 SL tire inflated with 93% nitrogen and topped off with air.

FIG. 11
FIG. 11

Partial pressure evolution over service life for P235/75R15 SL tire inflated with 96% nitrogen and topped off with air.

FIG. 12
FIG. 12

Comparison of oxygen permeation in P235/75R15 SL over tire lifetime showing the benefit of nitrogen inflation and maintenance of tire nitrogen purity.

FIG. 13
FIG. 13

Initial IPLR for P235/75R15 SL tire inflated with nitrogen.

FIG. 14
FIG. 14

Partial pressure evolution over service life for P235/75R15 SL tire inflated with 93% nitrogen and topped off with inflation gas at 95% purity.

FIG. 15
FIG. 15

Partial pressure evolution over service life for P235/75R15 SL tire inflated with 96% nitrogen and topped off with inflation gas at 98%.

FIG. 16
FIG. 16

Partial pressure evolution over service life for P235/75R15 SL tire inflated with 93% nitrogen and topped off with inflation gas at 100%.

FIG. 17
FIG. 17

Comparison of oxygen flow curves over the service life for P235/75R15 SL tire.

FIG. 18
FIG. 18

Service life oxygen flow across P235/75R15 SL tire for various initial nitrogen purities and top-off gases.

FIG. 19
FIG. 19

Comparison of IPLR in P235/75R15 SL tire for nitrogen inflation with various maintenance strategies.

FIG. 20
FIG. 20

Service life oxygen flow across LT245/75R16 LRE tire for various initial nitrogen purities and top-off gases.

FIG. A1
FIG. A1

Cross-section development for estimation of (A/V) ratio.

FIG. A2
FIG. A2

Comparison of estimated and experimentally determined (A/V) ratios for passenger car tire sizes reported by Costemalle.

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