To find suitable optional tire sizes, you need to check the sticker on your driver's side doorjamb. This sticker shows the tire size recommended by the manufacturer for your *specific* Astro van. This is your starting point.
From there, you can look at slightly different sizes that maintain a similar overall diameter. A tire size calculator (easily found online) is helpful for this. You'll want to stay within a +/- 3% difference in overall diameter to avoid speedometer inaccuracies and potential drivetrain issues.
Important Considerations:
* Load Capacity: The new tires must have a load rating equal to or greater than the original tires.
* Speed Rating: The speed rating should be appropriate for your driving habits.
* Overall Diameter: Maintaining the correct overall diameter is crucial for accurate speedometer readings and proper drivetrain operation.
* Rim Width: The tire's width must be compatible with your existing rims.
In short: Don't just pick a size from a list. Start with your vehicle's recommended tire size (from the doorjamb sticker), and then use a tire size calculator to explore slightly different sizes, ensuring they meet the above criteria. Consult a tire professional if you are unsure.
