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"Hard" and "Soft" mean different things to different tire manufacturers. I wanted to start a thread where we can share data to understand how compounds compare between brands. If you have a durometer please share your readings and we can create a master list.
Durometer measurements are in Shore A. I also included weight measurements I have made.
The compound definitely gets harder after a number of heat cycles. I measured a well used Pirelli medium at 85A. Everyone always talks about how used tires lose grip because they lose their sharp edges, but I also wonder how much of that is the compound not being compliant due to heat cycles.
Post up your measurements below and I will add them to the master list. If I remember I will try to bring my durometer to the rallycross at Glen Helen on 4/25 if anyone wants to take some data.
| Brand | Model | Size | Compound | Durometer | Weight (lb) | Notes |
|---|---|---|---|---|---|---|
| MRF | ZDM3 | 175/70R15 | Soft | 62A | 23 | New at 65F |
| Pirelli | K | 175/70R15 | Medium (K4) | 60A | 28 | New at 65F |
| Yokohama | A053 | 150/625R15 | Soft (A50) | 75A | 24 | New at 65F |
Durometer measurements are in Shore A. I also included weight measurements I have made.
The compound definitely gets harder after a number of heat cycles. I measured a well used Pirelli medium at 85A. Everyone always talks about how used tires lose grip because they lose their sharp edges, but I also wonder how much of that is the compound not being compliant due to heat cycles.
Post up your measurements below and I will add them to the master list. If I remember I will try to bring my durometer to the rallycross at Glen Helen on 4/25 if anyone wants to take some data.
