My mother in law has a 2001 Jeep Wrangler with a four cylinder engine. It s a dog, especially going uphill, and she lives in the mountains.?

She would but not a lot and she would get poorer mileage.

First, when hill climbing, turn off the Air Conditioning.

Next when she is going up hill and finds it is still slowing down, if it is an automatic and there is an Overdrive button on the gear shift, she should turn the Overdrive off. Then put it back on at the top of the hill.

Leaving it off all the time will kill her gas mileage.

Alternately, if there is no Overdrive button, drop it from D to 2 on the gear selector while hill climbing.

If it has a manual transmission, downshift a gear.

Finally, realize that it is no crime if you have to slow down to 50 when climbing a mountain.

Best of all, these solutions do not cost anything.

You bet, the '01 Wrangler came stock with either 205/75-15 or 225/75-15 sized tires. The use of either size would give the Jeep at least mild improvement with dealing with the hills.

Hi if only faults such as a worn out ole engine could be fixed by changing the size of wheels. unfortuneately this needs a lot more work and expenditure than just swapping wheels over.