New tires

[JJQuillian]

I changed my tires from 275/55R20 to 285/60R20, should I really be concerned about programming the speedometer??

Thanks,

Jeremy

 

[crash68]

The difference between the tire sizes:

At 70 mph you'll actually be going 73.4 mph

 

[TestPilot57]

Yes, no, maybe so. Depends on if being accurate matters to you and how arithmetically inclined you are if so.

 

[TestPilot57]

FWIW I printed out a list of various speeds for my wife when she had to drive my Ram a few hundred miles.

i.e.
50 = 46 on speedo
60 = 56 on speedo
65 = 60 on speedo
etc

For myself, I generally drive at the posted speed according to my speedo, or about 8% over. But I may adjust up or down a mile or two depending on traffic (if there is any...).

 

[gwilburn]

FWIW I printed out a list of various speeds for my wife when she had to drive my Ram a few hundred miles.

i.e.
50 = 46 on speedo
60 = 56 on speedo
65 = 60 on speedo
etc

For myself, I generally drive at the posted speed according to my speedo, or about 8% over. But I may adjust up or down a mile or two depending on traffic (if there is any...).

That wouldn't work for my wife ...

Start at 75 = 70 on speedo and keep going

 

[TestPilot57]

That wouldn't work for my wife ...

Start at 75 = 70 on speedo and keep going

That's why I ended with "etc."...

 

[Tulecreeper]

FWIW I printed out a list of various speeds for my wife when she had to drive my Ram a few hundred miles.

i.e.
50 = 46 on speedo
60 = 56 on speedo
65 = 60 on speedo
etc

For myself, I generally drive at the posted speed according to my speedo, or about 8% over. But I may adjust up or down a mile or two depending on traffic (if there is any...).

I'll drive 5 MPH over, up to a posted limit of 65. Starting at 65, I just stick with the posted limit. Any faster doesn't get me to my destination really any faster.

 

[TestPilot57]

I'll drive 5 MPH over, up to a posted limit of 65. Starting at 65, I just stick with the posted limit. Any faster doesn't get me to my destination really any faster.

If you're driving 25,000 miles, an extra 1 MPH will get you there in approximately 6 hours less time. So if you drive 25,000 miles per year, in 20 years you could bill an extra $27,000 FOR EVERY MILE PER HOUR if you're a lawyer billing @ $225/hr (pretty reasonable around here). Or, $135,000 at 5 over; enough to pay for your new truck and enough left over to buy a bauble for your SO.

 

[Tulecreeper]

If you're driving 25,000 miles, an extra 1 MPH will get you there in approximately 6 hours less time. So if you drive 25,000 miles per year, in 20 years you could bill an extra $27,000 FOR EVERY MILE PER HOUR if you're a lawyer billing @ $225/hr (pretty reasonable around here). Or, $135,000 at 5 over; enough to pay for your new truck and enough left over to buy a bauble for your SO.

25,000 miles is 4 round-trips across the US, and about 30 days of driving. If it only takes me an extra 6 hours in a 30-day period to arrive at a destination 25,000 miles away, I'll live with that.