When selecting PVC tarpaulin, thickness and strength are critical factors affecting durability, weather resistance, and suitability. Here’s a detailed guide:  

1. Understanding Thickness  
Thickness is measured in millimeters (mm) or "si" (1 si = 0.01mm), typically ranging from 0.35mm to 1.2mm.  

Thickness Grades & Applications  
| Thickness   | Strength               | Best For                          |   
| 0.35–0.5mm | Lightweight, flexible      | Short-term covers, small banners      |  
| 0.5–0.8mm  | Moderate strength          | Vehicle ads, event tents, canopies    |  
| 0.8–1.2mm  | Heavy-duty, tear-resistant | Construction hoardings, billboards    |  

Thickness Selection Tips  
- Thicker ≠ Better: Excess thickness adds weight (e.g., vehicle ads need flexibility).  
- Check Base Fabric: Thickness must match inner polyester grid (e.g., 500D/1000D) to prevent delamination.  

2. Key Strength Factors  
Strength depends on fabric + coating:  

Base Fabric (Skeleton Layer)  
- Polyester: Common (500D–1500D); higher denier = higher tensile strength.  
- Fiberglass: Extreme weather (e.g., typhoon-prone areas).  

Coating Technology  
- Double-sided PVC: Waterproof, anti-mold.  
- UV Layer: Prevents fading (ask for UV ratings, e.g., 5/8 years).  

Durability Tests  
- Wind Resistance: Premium tarps withstand ≥8级 winds (e.g., 1mm + 1000D resists 级12 winds).  
- Tear Strength: ≥800N (EN ISO 13937 standard).  

3. Practical Buying Tips  
Match Needs to Specs  
- Short-term: 0.5mm + 500D (budget-friendly).  
- Long-term: 0.8mm + 1000D + UV layer (weatherproof).  

Quality Tests  
- Hand Feel: High-quality tarps are uniformly thick, fold without cracking.  
- Burn Test: Polyester melts with black smoke (flame-retardant PVC self-extinguishes).  

Cost-Effective Picks  
- Construction ads: 0.6mm + 800D (1–2 years).  
- Premium vehicle ads: 0.8mm + UV coating (longevity).  

4. FAQs  
Q: Why do prices vary for the same thickness?  
A: Base fabric density, coating quality (e.g., imported PVC), UV treatment differ.  

Q: Best for rainy climates?  
A: Choose ≥1.0mm + double-sided coating to avoid leaks.  

Q: Lifespan?  
A: Standard: 2–3 years; premium: 5–8 years.  

Summary  
- Lightweight: 0.35–0.5mm (short-term).  
- Balanced: 0.5–0.8mm (most ads).  
- Heavy-duty: 0.8–1.2mm (harsh weather).  

Always request test reports for fabric density, coating thickness, and wind resistance!