Let me think about this.
Since you did not specify the manufacturer; I am using the load sheet for Maxxis.
The OEM ST 225/75R/15 Load range C tires are rated at 2150# at 50 PSI.
1) The ones you want to put on it ST 205/75R/15 Load Range D are rated at the same load capacity (2150#) at 65 PSI. So from a Load Supporting perspective there is no difference BUT you won' have the "pad" you were looking for.
2) The aspect ratio of the new tire (75R) is the same BUT with the narrower tread width the tire is shorter.
The new 205/75/15 tire is 8.07 in wide and 27.1 inches tall
The OEM 225/75/15 tire is 8.86 in wide and 28.3 inches tall
Tire Size Calculator
I think it is a safe swap since it will carry the load and physically fit the wheel well. They will rotate more per mile, and will wear out sooner, but should be safe, IMO.
Obviously if you can sell them for a good price and can bear the cost of upgrading them you should look for a 225/75/15 load range D tire to get you that cushion again.
You can repair that radial if it is a center of tread clean punch with an "off rim" repair and should give you great service for the remaining life of the set while you figure out what to do.
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