Since we were going to be driving the car more, we decided to finally get a decent set of tires. The old tires were old and dry rotted. The old tires were only suited to hold air and a few trips around the neighborhood. The only problem was we had no idea what type of rims we actually had. We knew the rims were a Panasport rims but we didn’t know the exact rim. There are offsets and rim thickness which were mysteries. The tires we had were a 195/55-15 and were way too wide for what we wanted and we had to essentially start over so we couldn’t get too much information from them besides the rim size.
Since I didn’t know too much about rim and tire fitment I started by measuring the approximate rim size with a level and a tape measure. I realized the rim size is based on the inside lip of the rim. This helped give me a gauge of the rim size, which I estimated in and around 7″. I searched all over the rim for something signifying the rim width and offset. I found an identifier marking but it didn’t tell me anything at all. It just let me know what type of Panasport rim it was. The Panasport website was no help either. They simply don’t have a great online presence. There was also a sticker that should have the offset noted but it was left blank. The only way we could actually know the rim size is by taking it to a tire shop where they can measure the width with a large custom caliper. We took a tire to Pep Boys and they measured the width of the rim at 6″ wide.
Something I didn’t know was the width of the rim is taken from the bead seat to the bead seat and the diameter is also taken from bead seat to bead seat. If you absolutely don’t know the width of the rim, and the tire is seated, you will either need to remove the tire or take it to a shop and have them use their custom caliper measuring tool. I had to laugh at myself because I was measuring from the outside width. You live and you learn.
This was also good news since it is widely known in the Sunbeam Alpine community, that if you go any larger than a 6″ wide rim, the tire will heavily bind on the front bodywork. Even with the 6″ rims, the front valence will need to be trimmed which we are planning to do. Now that the size of the rim was sorted, we could finally decide what tires we wanted to buy.
Since the car would not be a drag car or a track/autocross car, my dad wanted something less aggressive and slimmer tire. We used several resources to determine which was the slimmest tire we could put on the rim. We both discovered through our research that the slimmest safe tire was a 175mm wide tire. Next up, was trying to mimic the aspect ratio and overall thickness of the tire since we just set the speedometer to match the previous tire setup. The previous tire height was 23.4″ so we wanted to be close to that width.
After a ton of research and trips to Pep Boys inquiring about tire availability and stock, we finally found a perfect tire online. We found a Kumho tire, which was oddly enough, the same model type of tire we had on the car before. The tire has an overall width of 24″ so we are barely wider than the existing 23.4″ tire. Since all of the boxes were checked, we decided to purchase Kumho Ecsta PA31 175*65R15 tires from Amazon.
We decided to purchase the tires from Amazon based on a tip from someone at my work. because of the price but also Amazon has a great program where you can buy the tires and have them sent to a tire installation retailer such as Pep Boys. Amazon also includes the option to mount and balance in the cost of the purchase and in shopping around all of the tire suppliers, this was dramatically lower than anything the typical suppliers could beat. The only drawback is if the tire gets a nail or needs a rebalance, they will most likely charge you but since the car would not be on the road too much, the cost savings was worth it. During checkout simply add mount and balance to the order and choose an installer where the tires are to be sent. Then, schedule the appointment with the installer. All of this is done during the purchase of the tires and is fully completed on the Amazon page.
Once purchased and the appointment with Pep Boys scheduled, I followed the delivery of the tires to Pep Boys via Amazon. I called Pep Boys just to make sure the tires arrived and sure enough, they made it. The day of the appointment came and we had a small issue with the installation. Since this service is so new, the person approving the work had some trouble but it didn’t take too long to get it all sorted. All in all the service worked and the price was way cheaper than anything the brick-and-mortar stocks could match. I would definitely recommend the service.
This was an interesting part of the project and one I wasn’t expecting to be at all complicated. Part of the problem was my ignorance of tire and rim sizing. The purpose of this project was to learn and boy did I get an education. We learned that 6″ wide rims are the way to go with rubber widths from 175mm to 195mm. We also learned the valence would need to be trimmed. Lastly, I learned a cheap and simple way to get tires from Amazon. My dad was smitten with the way the tires blend in to the rim. He wanted to avoid the sidewalls bulging away from the rim and according to him, we nailed it. With my dad now satisfied with the tires and baring a complete and utter mechanical failure, the car was safe to drive. The next post will deal with an engine tune and dyno test. Motor on.