I've got a 1500 QC 4x4 with 17in rims 245/70/17. It's time for new tires and I was considering upsizing to 265/70/17 and was wondering what were the tradeoffs in that switch? Would I get better stop/start traction but worse gas mileage? Will the added size and wt change the handling characteristics?

 

265/7017 was the optional size for some of those 1500s, so it should work fine. Bigger tires give you more traction for acceleration, braking, and turning. The increase in height can change the handling a bit. The weight difference will slightly impact the fuel mileage, although the taller tire gives slightly taller gearing, and may offset this in highway use. The bigger tires will also look better

 

taller tires will give less acceleration. The 265/70/17 is about and inch taller and an inch wider than a 245/70/17. So you will have a bit less power when accerlerating.

 

Dacaur, you are correct. Taller tires = taller effective gear ratios = slightly reduced acceleration

 

How will larger tires affect my speedo? If tires are 5% bigger does that mean my speedo will indicate 5% slower than I am actually going?

 

Correct. The % difference in overall diameter will be the % difference in speedometer and odometer readings.