[260e crusier]

Why is my stack of 235/45/17 half an inch shorter than the stack of 215/55/16? I measured with a straight edge across the top.

 

[260e crusier]

From my calculation, 235 should be approximately 18.5" and 215 should be 17". Actual measurements for 235 is 17.75" and for 215 is 18.25" (measurements has not been inversed).

 

[khomer2]

Your base /ground is unlevel?


Perhaps the wheel (comparison) profiles are not the same?
same identical tires?

 

[raymond-]

Note that even within the same advertised tire size, plus/minus variation is the reality on the final production of any tire....even more so between cross make/model tires. That said, I would also add PSI and temperature factors during inflation, tire age

 

[brauhaus]

You can't really compare. Even tires of the same width rating have oftentimes wildly varying tread, section, and overall widths. Your 215's likely have wider real world overall width than your 235's.

 

[wlb50]

I'll tell you a little story my local MBCA Section heard from a dealer service manager years ago.

They had a problem car, a W140 S500.

And at precisely the same speed, some 60+ mph, the cruise control would cut out.

Every time.

Predictably.

They tore the car apart and asked around - nothing.

They finally came to the answer.

The owner had bought a new Michelin tire in the appropriate same size, made in the US and the other 3 tires were the same Michelins, same size, made in Europe.

The new tire was on the rear axle and its circumference was just a mm or so different from the adjoining Michelin on the other side.

And what that was doing was confusing the computer with different rotation speeds on each side of the axle, until it programmatically "threw up its hands" and gave up. Could have been tire wear on the other side, I didn't ask him. Didn't ask him which side was smaller.

Point is among different makes and even different molds, you won't get identical dimensions at times.

 

[260e crusier]

I knew there was a variance between stated and actual size. What I didn't expected was the stack of 215 tires being significantly wider than the 235.

The 235 width is .375" smaller (each tire) between calculated and actual. For the 215, it's .625 wider. Combining the two explains the half inch difference between the two stacks

 

[raymond-]

I'll tell you a little story my local MBCA Section heard from a dealer service manager years ago....

I've experienced this ever since I installed w211 staggered wheels onto my w210 the past 10 years. Once the Conti Sport Contacts wear down I may rethink the wheel/tire configuration. Fortunately I am an old school driver so much that I rarely use the cruise control given the traffic environment around me. My E320 is the only auto transmission vehicle I own so I'm just giddy being able to drive w/o shifting and having a burger in that hand.