This tire-and-wheel combo is ready for serious mileage. The Tamarack ST225/75R15 radial tire has an 8-ply rating and handles up to 2,540 lbs at 65 psi, while the matching aluminum wheel is rated for 2,830 lbs. With an M speed rating of 81 mph, it’s built to stay cool and stable on long hauls. Both the tire and wheel meet DOT, FMVSS, and SAE J1204 standards for confidence at highway speeds.
Every setup comes bead balanced with internal tire balancing beads already in place. There’s no need for external weights or shop balancing—just bolt it on and roll. That internal balance helps deliver a smoother ride and extended tread life over time.
Saltwater spray, road grime, and wet weather don’t stand a chance against this rustproof aluminum wheel. Its Condor Series 6-spoke gunmetal gray design is coated with an automotive-grade clear coat to protect against scuffs and scratches. Steel inserts in each lug nut well keep the wheel tight on the hub and prevent wear around the holes, so it stays secure season after season.
The Tamarack radial tread uses double steel belts and double nylon piles for strength, with sipes that cut thin channels into the rubber to move water away from the contact patch. Those grooves improve traction during wet, snowy, or icy conditions while reducing heat buildup for longer tread life on the road.

If something happens out on the road, you’re backed by Tamarack’s 1-Year No Excuses Guarantee and complimentary roadside assistance for two years. The guarantee covers any damage not already under warranty and even includes labor cost for mounting a replacement tire. With 24/7 flat service across the U.S., Canada, and Puerto Rico, you can travel knowing help is always close by.
1. Count the lug holes
Look at the wheel hub or the back of the wheel and count how many lug holes there are(also called bolt holes).
Common configurations include: 4-lug, 5-lug, 6-lug and 8 lug
2a. For even lug counts (4-lug, 6-lug, 8-lug)
Measure from the center of one lug hole directly across to the center of the hole opposite it.
Common configurations: 4 on 4", 6 on 5.5", 8 on 6.5"
2b. For odd lug counts (5-lug)
Measure from the center of one lug hole to the outer edge of the hole directly across (not center-to-center since there's no directly opposite hole).
Common configurations: 5 on 4.5" (most popular), 5 on 5", 5 on 4.75", 5 on 5.5"
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Hello everybody, this is Jeff at etrailer.com. Today we're gonna take a look at this Castle Rock ST225/75R15 Radial Trailer Tire in a load range D mounted on this 15" gunmetal gray aluminum wheel with a 6 on 5 1/2" pole pattern. Now this tire wheel assembly is ideal for RVs, campers, and trailers. Gonna zoom in and we'll first talk about the wheel itself. The wheel on this, it's an aluminum wheel. It's very durable, lightweight, and rustproof and this one is the Condor series, which is a split 6-spoke design, and as we mentioned, it's in a gunmetal gray, and you can see it in the back.
Now they do use an automotive grade clear coat finish on the front to protect the wheel from any scuffs and scratches, and they do use steel inserts in your lug nut wells right here where your lug nuts go. This is designed to help keep the wheels securely in place on your trailer hub, prevents the holes from elongating and wearing down, and eliminates the need for a constant re-tightening of your lug nuts. Now the wheel itself, the dimension on it, the diameter, which is always measured inside to inside straight across is 15". The width on just the wheel by itself is 6" wide. And we mention this wheel has a bolt pattern of 6 on 5 1/2" and if you wanna measure that on a wheel, that's an even number of lugs, like in this case six, all you have to do, because the lug holes are directly across from each other, just pick any lug hole, let's say this one, measure from the center of that directly across to the center of the lug hole across from it.
On this it'll measure 5 1/2" so it's a 6 on 5 1/2" bolt pattern. Does use a wheel lug size of 1/2" by 20, and the weight capacity on just the wheel by itself is 2,830 pounds. And one thing I do wanna mention, if you look at the center of the wheel, there is no center cap in this. It is not included. If you do want a center cap, we do offer those separately.
And when you do get a center cap, you want it to have the same diameter as this pilot hole, which is 4.25" 'cause your center cap will go through this pilot hole when you install it. Now the tire on this is a Castle Rock Radial Tire. It is constructed with double steel belts, double nylon ply. Does use a nylon tread firming belt overlay around the tire to help prevent tread separation, and it is a radial ply tire, so it is great for highway use. If you look at the tread on this, they do have the siping on the tire tread.
Basically those are the cuts that are on the tire blocks and what that does is it breaks up the water underneath the tire to improve the traction during wet, snowy, or icy conditions. This tire is an ST tire, which stands for Special Trailer Tire, uses the sturdy sidewall so they can handle heavy loads and it is created specifically for trailers. It's not intended for use on other vehicles. The tire size, which will be stamped on the sidewall ST225/75R15. The R again means it's a radial tire. The section width on this tire is gonna be right at 8.8 inches. The overall diameter from the bottom to the very top when it's inflated is 28.3. And this tire is a load range D, which means it's an 8-ply rated tire. Has a maximum load capacity of 2,540 pounds at 65 PSI. And I did wanna mention the trailer tire does have a speed rating on it and the speed rating is also stamped on the sidewall and where that is at is if you go right where the size was we went over, if you go a little bit further, you'll see it says speed rating L, and then it'll say in parentheses 75 miles per hour. Now this does offer a complimentary roadside assistance for two years. They give you flat tire service available 24/7 anywhere in the US, Canada, or Puerto Rico, and this whole assembly does meet the DOT Department of Transportation specifications. But that's gonna do it for the review on this Castle Rock ST225/75R15 Radial Trailer Tire in a load range D on the 15" gunmetal gray aluminum wheel with the 6 on 5 1/2" bolt pattern.
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