I have a 1990 B2600 that has 14" rims.Can I put 15" rims on and how do I find the right ones?Thanks

1990 Mazda B Series Pickup 6 lug 5.5 inch or 139.7mm Medium Offset

If you are determined to go to 15", you need a lower profile tire to come even close to stock, and that will change your gear ratios and speedometer accuracy. If off-set is changed the load carrying center is not where it should be and will destroy wheel bearings... A truck needs tall sidewalls... you can do this but IMO not recommended

it's 5 lug but I don't know what the 5.5 reference is? I had another mazda pickup that was lifted and I believe bigger tires but that was 20 yrs ago so I don't remember.I wanted to put bigger tires and a lift kit so I could carry about 1000# and not have it riding low.

Is that still a bad idea?

Ive had the b series for 10+ years and have done it all engine and body the rims are interchangeable with chevy 6 lug caddilac 6 lug Nissan 6 lug and some newer ford 6 lug The only problem you will run into is the wheel sets on the front hubs and rear axel....it takes approximately 25 minutes per side to push back studs and grind down the sets.....this allows for a larger center on the rim to fit properly

There is also a spacer where the top a arm mounts to adjust camber