Spyderman
New Member
I had 205/80 R16 on my 88" series III Diesel ehen I bought it they are the nearest modern equivilent to the original 6.5 x 16. I changed them to Michelin 7.50 x 16 XCL's fitted on LWB rims, the modern equivilent being 235/85R16 They are about 2 1/2 inches taller than the originals fitted. They make a difference of about 12% extra to the rolling cicumference. So you go down hills off road in low first a bit quicker, accelerate a bit slower but top end is pretty good if on the flat or down hill. Speedo also under reads.
Spyderman
New Member
Slob, Just Measured the Tyres. The 205's are 8" wide total but the 7.50 are more like 9" wide but the tread is only 7.5" wide maybe in old money they measured the tread width rather than the tyre width. To confirm though 7.50x16 are much bigger than 205/80R16 because I have a set of both.
if ye measure side wall width rather than tread width then rim size and pressure can have an effect on the measured width.. which is probelly why the manufactoers...manufacters.. the makers measure tread width.
the 7.50 have a dia of 31"
6.50s will be 29"
205/80 have a dia of about 29".
235/85 will be approx 32"
widths are
6.50 6 1/2
7.50 7 1/2
205 8
235 9 and a bit
i just quickly did that lot in me head so if anyone whats to get their calkeymalator out and do it exactly then go ahead.
the 7.50 have a dia of 31"
6.50s will be 29"
205/80 have a dia of about 29".
235/85 will be approx 32"
widths are
6.50 6 1/2
7.50 7 1/2
205 8
235 9 and a bit
i just quickly did that lot in me head so if anyone whats to get their calkeymalator out and do it exactly then go ahead.
Spyderman
New Member
I'm impressed to do that lot in your head, you should go on Countdown.
I think you're right though about manufacturer's probably measuring the tread width, which makes it more difficult to compare the old sizes with new as the old were probably crossply and had more of a balloon profile rather than newer radials which tend to have squarer profile sidewalls. So the old size 7.50 even though 1/2" narrower tread than a 205 - 8" is physically a bigger tyre. I agree with you that the 7.50x16 is about 2" taller than a 205/80R16. Instant 1" extra ground clearance, Yippee.
I think you're right though about manufacturer's probably measuring the tread width, which makes it more difficult to compare the old sizes with new as the old were probably crossply and had more of a balloon profile rather than newer radials which tend to have squarer profile sidewalls. So the old size 7.50 even though 1/2" narrower tread than a 205 - 8" is physically a bigger tyre. I agree with you that the 7.50x16 is about 2" taller than a 205/80R16. Instant 1" extra ground clearance, Yippee.
Spyderman
New Member
Just thought about it some more didn't factor in the aspect ratios.
205/80R16
205mm x 80%=164mm sidewall height
Total 164 + 164 +407rim = 735mm / 28 15/16"
6.5(165mm) x 100%= 165 sidewall height
Total 165 + 165 + 407 = 737mm / 29"
235/85R16
235mm x 85%=200mm sidewall height
Total 200 + 200 + 407 = 807mm / 31 3/4"
7.50(191mm) x 100%= 191mm sidewall height
Total 191 + 191 + 407 = 789mm / 31 1/8"
Had to use a calculator.
205/80R16
205mm x 80%=164mm sidewall height
Total 164 + 164 +407rim = 735mm / 28 15/16"
6.5(165mm) x 100%= 165 sidewall height
Total 165 + 165 + 407 = 737mm / 29"
235/85R16
235mm x 85%=200mm sidewall height
Total 200 + 200 + 407 = 807mm / 31 3/4"
7.50(191mm) x 100%= 191mm sidewall height
Total 191 + 191 + 407 = 789mm / 31 1/8"
Had to use a calculator.
