Table 4A

Comparison of Understeer Gradient Values Determined by Different Techniques
Lightly Loaded (Curb + Driver + Instrumentation) Condition vs. GVWR Condition
Test Condition Lightly Loaded Condition GVWR Condition
Test Direction
Test Vehicle Clockwise Counter-Clockwise Clockwise Counter-Clockwise
  95% Confidence Limits   95% Confidence Limits   95% Confidence Limits   95% Confidence Limits
Average Lower Upper Average Lower Upper Average Lower Upper Average Lower Upper
'96 Ford Explorer w/Firestone Tires                        
Firestone Analysis 2.07     2.01     1.43     1.85    
Change from LL             -0.64     -0.16    
% Change from LL             -30.92%     -7.96%    
VRTC Analysis 1.93 1.38 2.48 1.99 1.80 2.18 1.59 1.35 1.83 2.03 1.57 2.49
Change from LL             -0.33     0.04    
% Change from LL             -17.21%     2.07%    
                         
'96 Ford Explorer w/Goodyear Tires                        
Firestone Analysis 1.81     1.87     1.69     1.85    
Change from LL             -0.12     -0.02    
% Change from LL             -6.63%     -1.10%    
VRTC Analysis 2.02 1.94 2.10 2.19 1.69 2.69 2.04 1.87 2.22 2.14 1.99 2.29
Change from LL             0.02     -0.05    
% Change from LL             1.22%     -2.41%    
                         
'00 Ford Explorer                        
Firestone Analysis 2.31     2.08     2.23     2.2    
Change from LL             -0.08     0.12    
% Change from LL             -3.46%     5.77%    
VRTC Analysis 2.38 2.08 2.69 2.28 2.13 2.44 2.36 1.87 2.85 2.48 2.23 2.73
Change from LL             -0.03     0.20    
% Change from LL             -1.10%     8.76%    
                         
'96 Chevrolet Blazer                        
Firestone Analysis 5.10     3.48     3.88     4.7    
Change from LL             -1.22     1.22    
% Change from LL             -23.92%     35.06%    
VRTC Analysis 5.37 4.75 5.99 4.83 0.60 9.06 4.42 3.29 5.54 4.98 3.64 6.33
Change from LL             -0.95     0.15    
% Change from LL             -17.77%     3.15%    
                         
'01 Jeep Cherokee                        
Firestone Analysis 4.81     5.07     5.32     4.76    
Change from LL             0.51     -0.31    
% Change from LL             10.60%     -6.11%    
VRTC Analysis 5.06 4.37 5.75 5.46 4.62 6.29 5.37 4.45 6.29 5.56 4.77 6.34
Change from LL             0.32     0.10    
% Change from LL             6.23%     1.81%