diff --git a/tire/tire_81.6_50.scad b/tire/tire_81.6_50.scad
index 31a7269..bc7d607 100644
--- a/tire/tire_81.6_50.scad
+++ b/tire/tire_81.6_50.scad
@@ -157,7 +157,7 @@ difference() {
     cylinder(r=R_I+B+THICKNESS, h=W);
   }
   // lateral protector
-  for (i = [1 : N_L])
+  if (N_L > 0) for (i = [1 : N_L])
     translate([0, 0, -PROT_L_WIDTH/2+i*W/(N_L+1)])
       difference() {
         cylinder(r=R+1, h=PROT_L_WIDTH);
@@ -166,12 +166,12 @@ difference() {
         translate([0, 0, -0.1]) cylinder(r=R-PROT_DEPTH, h=PROT_L_WIDTH+0.2);
       }
   // angular protector
-  for (i = [1 : N_A])
-    rotate([0, 0, 360/N_A*i]) protector_single();
+  if (N_A > 0) for (i = [1 : N_A])
+    rotate([0, 0, 360/N_A*i]) protector_angular();
 }
 }
 
-module protector_single() {
+module protector_angular() {
   difference() {
     union() {
       translate([(W/2)/2, 0, W/2]) rotate([0, -45, 0])
@@ -180,8 +180,6 @@ module protector_single() {
         cube(size=[PROT_A_WIDTH, R+4, PROT_A_WIDTH+sqrt((W/2)*(W/2)*2)]);
     }
     translate([0, 0, -0.5]) cylinder(r=R-PROT_DEPTH, h=W+1);
-    translate([0, 0, W]) cylinder(r=R+10, h=10);
-    translate([0, 0, -10]) cylinder(r=R+10, h=10);
   }
 }