Is it necessary to change tires when changing rims?

[DeBrooklyn]

Changing rims does not necessarily require changing tires. For modifications, you first need to determine the specifications of the modified tires, such as 205/55R16. Then, based on this specification, refer to the national standards to find the corresponding rim width that matches this specification. This will help you determine the appropriate rim size. Below is additional information: For example, for 195/65R15, according to the national standards, the compatible allowed widths are 51/2J and 61/2J, with a measured width of 6J. Therefore, the rim width options are: 51/2J15, 61/2J15, or 6J15. For 225/65R15, according to the national standards, the compatible allowed widths are 6J and 7J, with a measured width of 61/2J. Therefore, the rim width options are: 6J15, 7J15, or 61/2J15. From this, it can be concluded that if the original rim width is 51/2J15 or 7J15, they cannot be used interchangeably. Additionally, the rim offset must also be considered.

[JasonMarie]

I just installed a set of 18-inch wheels on my car. Can I keep using the old tires? Actually, it depends. I've researched this specifically—if the wheel diameter remains unchanged, you can absolutely keep the original tires. But if you're upgrading the wheel size, say from the factory 16-inch to 18-inch, you must replace them with larger-sized tires accordingly. Here's a pitfall to watch out for: wheel width is also crucial. For example, if you switch to wider wheels but the old tires aren't wide enough, the sidewalls will be forcibly stretched and deformed. My neighbor's tire sidewall cracked because of this. Additionally, incorrect bolt patterns may cause rubbing against brake calipers, and loose bolts pose even more serious risks. My advice: when changing wheels, bring your old tires to a modification shop. Have the mechanic adjust the wheel offset while monitoring with a tire pressure gauge—it'll save you a lot of hassle.

[JosieLee]

I often get asked this question by fellow car enthusiasts, so I'll share a few words based on years of modification experience. Changing rims and tires aren't necessarily a package deal, but compatibility is crucial. The rim width parameter (J value) determines the suitable tire width range - for instance, a 7J rim fits 215-225mm wide tires. If your stock tires are 215mm wide, they might barely work on 7.5J rims, but mounting them on 8J rims would be like overstretching a rubber band, accelerating wear. Special warning for stance enthusiasts: extreme camber with narrow tires increases the risk of bead unseating. The most extreme case I've seen was someone who changed rims without upgrading tires - the tire completely separated from the rim over a speed bump, bending the rim edge. After modification, I recommend marking the rim edge with chalk and checking for rub marks after a few kilometers of driving.

[MacElias]

Last time at the track day, I learned a few tricks from the mechanic. When changing wheels without replacing tires, there are two situations to fear the most: one is when the new wheel's center bore is smaller than the original, forcing it on will cause the bearings to fail prematurely; the other is when the ET value deviation exceeds 5mm, causing the tire to rub against the fender during turns. Actually, a wheel diameter difference within 2cm is not a big issue, the key is whether the tire's aspect ratio can be adjusted. For example, switching from 225/50R17 to 225/45R18 results in an overall diameter difference of only 4mm, which doesn't affect the speedometer. Here's a money-saving tip: when transferring the original tires to the new wheels for dynamic balancing, ask the mechanic to use a tapered locating cone for fixation, which can keep the balance weight error within 5g.