Hi all,

I have an '87 Westy, auto, with Yokohama LT 195/75R-14 Y356 D tires.
Being as they are bigger than the 185s, I always figured that the
speedometer was a few mph off. When I picked up my van yesterday,
something felt very wrong to me. I felt like I was pushing the van
really hard to get up to Interstate speed, 70 mph, and I was passing a
lot of people at 63-65 mph.

Today, I had my wife download a speedometer app to her phone and we
checked our actual speed against what my speedometer was reading. We
found it was off by 5 mph at lower speeds and off by 7 mph at higher
speeds.

So, I assume that I have three options here:
1) Adjust my speed according to what I know the discrepancy to be;
2) Change the gearing so that my speedometer is accurate once again?;
3) Change the size of my tires.

Since I just bought 2 new tires, that last option is not one that I'm
going to pursue any time in the near future, but may consider when the
time comes to replace tires.

In any event, I thought this information might be useful to anybody
who's running this size tires on their vans.

Drive safe, y'all!
Marc Perdue

PS--This was a real eye-opener for me when I considered the time or
two when I actually thought I got up to 85-90 . . . =8^O