No!235/40/19 is the same rolling circumference as 245/40/19 though surely…?
235/35/19 is different rolling circumference to 245/40/19 no…?
The '40' part is the sidewall size as a percentage of the width. So the same 40% means 94mm for the 235 width (235 x 0.4) and 98mm for the 245 width (245 x 0.4).
235/35r19 would have an even smaller sidewall of 82mm (235 x 0.35).


















