Tire height vs. gear ratio relationship

[Buick Beginner]

Good Evening Gentlemen,
Recently I discovered my BFG DR's were down to the wear bars so I decided to go with a new set of Nittos. However I decided to go with 275-60's instead of 275-50's as I had before. The car seems to have some different characteristics than before. First off please bear in mind that these tests are all "seat of the pants" tests.
First, the old set up: OK, 1st gear punch from 5 MPH would spin all the way through first and very deeply into second. Occasionally spinning all the way until 3rd gear. It was no doubt thrilling but unproductive as far as racing goes.
New set up: First gear punch from the same 5 MPH gives a short squeal and good acceleration. I do notice I'm getting just a few lights on my knock gauge, (no KR though). So I had to turn the alky up just a bit.
Now, based on this I have a few questions. The lack of spinning leads me to believe that I'm getting more "bite" with the 275-60's, but I'm concerned that it may also be that I've changed the gear ratio enough to cause the car to have to "lug" itself along. Wouldn't the increase in alky indicate that the engine is being lugged? Am I still in the safe zone for gear ratio? Or do I need to step up to a 3.73 ratio? Experts chime in please. - BB

 

[toofastforyou]

It is true that if you're using a taller tire, you will lose a little power coming off the line, but at the same time, it should give you a slightly better top end speed. If you feel that the car is too lazy from a standing start, then maybe you could benefit from a higher gear ratio. It all comes down to having to making a compromise between of-the-line power vs. top-end power... Only you know how the car feels with the taller tires compared to how it felt with the shorter ones.
If you ever want some gears, I have a good used set of 3.90's for $100...
'bye, Claude

 

[UNGN]

Don't change the gear ratio!!!, keep the 3.42's.

Taller tires are harder to spin because of reduced gear reduction, but actually are easier to spin at the buig end of the track (where a TR's torque fall off a cliff) Of course there is less knock when a tire's spinning (except for false knock) because there is less load on a spinning tire than on one that is hooked up.

With street tires, its no contest, 28" tires are always faster than 26" tires.

 

[Rickracer]

A lot of folks consider the contact patch of a tire to be based on width....

...which it is, but a taller tire will also have a "longer" contact patch as well. If they are the same width but taller, you have a greater contact patch area, hence more traction.

 

[Buick Beginner]

Suspected

UNGN,
I knew you would chime in on that one! You suspension, gear, tire guy, you. BTW thanks for the great effort on your website and with moderating. - BB