Tires and wheels in Phoenix, written for the heat

Phoenix pavement spends long stretches of the year hotter than the air. Afternoon highs above 110°F are ordinary in June and July, and the asphalt on I-10, the Loop 101, and the Loop 202 holds that heat after sunset. Rubber ages faster here than it does in a mild coastal city: sidewalls chalk, small cracks open between the tread blocks, and a tire that still looks thick can be older than it should be. Monsoon storms then drop sudden rain on roads glazed with oil and dust. The same truck that commutes on the US-60 all week may spend a Saturday on gravel toward the Superstitions. One all-purpose answer does not cover that mix.

The guides below stay with the decisions drivers actually make: how to read a metric tire size, what bolt pattern, offset, and center bore change, when plus-sizing stays close to the original diameter, and how desert heat should change the way you think about compound, pressure, and age. Use the upsize calculator when you want the millimeter difference instead of a guess.

What this site will and will not tell you

Every page is general education for passenger cars, crossovers, and light trucks common in the Valley. It will not confirm that a specific wheel clears your brake caliper, control arm, or fender. Two trucks with the same badge can leave the factory with different brakes and different recommended pressures. The placard in the driver's door jamb, and the load and speed ratings molded into the current tire, outrank any example size used here.

Start with the size guide if the numbers on the sidewall are unfamiliar. Start with fitment if you are changing wheels. Start with heat, pressure, and replacement if the tires you have are staying on the vehicle. The calculator is the arithmetic companion to the plus-sizing guide, not a substitute for measuring clearance.

A year of Valley driving

The useful calendar is simple. In spring, set cold pressures again after the first week that stays above 100°F, and look at sidewalls that spent the winter in an open lot. Through summer, leave hot gauge readings alone and do not treat a chalky sidewall as a stain you can wash off. When the monsoon pattern sets in, usually from midsummer into September, tread depth matters more than it did in May, because a storm can drop enough water to float oil and dust across a freeway lane. Autumn is the calm stretch for replacing a set you have been watching. Winters on the valley floor rarely justify a dedicated snow tire. A drive up to Flagstaff is a different climate and a different decision.

The vehicles in that mix are part of the subject. Half-ton pickups, three-row SUVs, and crossovers share parking rows with work trucks that actually carry a load. A size printed on a neighbor's truck is not a specification for yours. P-metric and LT tires can look similar and still want different pressures. A wheel can share a lug count and still use the wrong offset, so the tire that cleared one fender meets the liner on another. Those distinctions are why the guides stay with the markings on the rubber and the hub, instead of with a list of model years.

How to use a page

Each guide states one decision: read a size, judge a wheel, compare a diameter, choose a tread for the miles you drive, set a pressure, or decide that a tire is finished. Examples use ordinary metric sizes so the arithmetic is visible. They are not a shopping list. Where a rule of thumb appears, such as keeping a diameter change near 3 percent, the page says it is a screen and not a measurement of your truck. The calculator repeats that limit in the result so the number and the warning stay together.

If you only have time for one pass before you talk to an installer, do it in this order. Copy the full size, load index, and date code from the current tire. Copy the pressure and original size from the door placard. If those sizes differ, calculate the diameter change. If the wheels are not the ones the truck came with, write down bolt pattern, offset, and center bore before you order another set. Then look at the old tread. Even wear means the alignment was probably close. A feathered edge or one bald shoulder means an alignment belongs with the new tires, or you will buy the same wear pattern again.