{"product_id":"the-airmatic-sentinel-mercedes-r-class-rear-air-springs","title":"The Airmatic Sentinel | Mercedes R-Class W251 Rear Air Spring Kit","description":"\u003cdiv class=\"product-narrative\"\u003e\n\u003cp\u003eA luxury car should not announce its age with a sagging corner. When an Airmatic system starts to droop, it is never just about comfort: it is about control, alignment, and the quiet dignity of a ride that still feels engineered.\u003c\/p\u003e\n\u003cp\u003eThe Airmatic Sentinel is a pair of rear air spring bags engineered for the Mercedes R-Class W251 (part 2513200425). Each bag is built with the layered rubber construction and reinforced fittings that the Airmatic system expects, so the replacement integrates cleanly with your existing compressor and valve block. No guesswork, no adapters that sort of fit.\u003c\/p\u003e\n\u003cp\u003eFit the pair, clear the fault code, and the W251 settles back to factory stance. The ride height returns, the rear end tracks true, and the car stops asking for attention on every bump.\u003c\/p\u003e\n\u003cp style=\"font-style: italic; color: #555;\"\u003eThe best suspension repair is the one you forget happened.\u003c\/p\u003e\n\u003cp\u003eThe kit also respects the reality of the job: each bag arrives ready to bolt in, with the bellows protected for shipping so no crease or fold weakens the rubber before it is even fitted. For shops that quote Airmatic work every week, that consistency translates into fewer comebacks and happier owners.\u003c\/p\u003e\n\u003c\/div\u003e\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #eee;\"\u003e\u003cdiv class=\"product-features\"\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul style=\"padding-left: 18px;\"\u003e\n\u003cli\u003e✦ Direct OE-style replacement for Mercedes R-Class W251 rear air springs (2513200425)\u003c\/li\u003e\n\u003cli\u003e✦ Pair set, so both rear corners are refreshed at once\u003c\/li\u003e\n\u003cli\u003e✦ Layered rubber bellows built for long service life under load\u003c\/li\u003e\n\u003cli\u003e✦ Reinforced fittings engineered to seat with the factory Airmatic hardware\u003c\/li\u003e\n\u003cli\u003e✦ Restores factory ride height and stabilizes rear-end tracking\u003c\/li\u003e\n\u003cli\u003e✦ Compatible with the existing W251 compressor and valve block\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\u003cdiv class=\"product-specs\"\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul style=\"list-style: none; padding: 0;\"\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Mercedes R-Class W251 (2513200425)\u003c\/li\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003ePosition:\u003c\/strong\u003e Rear left + rear right (pair)\u003c\/li\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Airmatic air spring bag\u003c\/li\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003eConstruction:\u003c\/strong\u003e Layered rubber bellows with reinforced end fittings\u003c\/li\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003eOE Reference:\u003c\/strong\u003e 2513200425\u003c\/li\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003eInstall:\u003c\/strong\u003e Bolt-on with factory hardware; air lines reconnect to OEM ports\u003c\/li\u003e\n\u003cli style=\"padding: 10px 0; border-bottom: 1px solid #eee;\"\u003e\n\u003cstrong\u003ePackage:\u003c\/strong\u003e 2 pieces per set\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\u003cdiv class=\"product-applications\"\u003e\n\u003ch3\u003eApplication Scenarios\u003c\/h3\u003e\n\u003cp\u003eThis kit serves W251 owners who have watched the rear of the car sink over time: R320, R350, R500 and AMG variants where the air springs have aged out. It is also the right call for independent shops and Airmatic specialists stocking proven replacements for one of the most common Mercedes suspension jobs of that generation.\u003c\/p\u003e\n\u003c\/div\u003e\u003cdiv class=\"product-faq\"\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Is this a direct fit for my W251?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: It is engineered as an OE-style replacement for the W251 rear air spring position (2513200425). Confirm your chassis code and that you are replacing the rear bags, and the hardware lines up with the factory mount points.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Do I need new air lines?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: Usually not. The fittings reconnect to the existing Airmatic lines. Inspect the line ends for cracks while you are in there, but the kit itself is self-contained.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Will this fix a sagging rear corner?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: If the sag is caused by a leaking air spring, yes: replacing both rear bags restores ride height and stops the compressor from cycling overtime.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Do I need to clear fault codes after install?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: After installation and a full ride-height recalibration, clear the suspension fault codes with a compatible Mercedes diagnostic tool so the system relearns its reference levels.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How long does installation take?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: A competent workshop typically completes the pair in a few hours. If you are not confident working with air suspension, have a professional do the swap and the recalibration.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\u003cdiv class=\"eastsupplier-promise\" style=\"background:#f7f8fa; border-left:4px solid #1a3a5c; padding:16px 18px; margin:24px 0;\"\u003e\n\u003ch3\u003eThe EastSupplier Promise\u003c\/h3\u003e\n\u003cp\u003eEvery product in our catalog is sourced directly from vetted manufacturing partners, inspected before dispatch, and shipped with tracking. If anything arrives damaged or does not match its listing, our support team responds within 24 hours with a replacement or a full refund. No forms, no waiting, no fine print.\u003c\/p\u003e\n\u003c\/div\u003e\u003cdiv class=\"product-gallery\" style=\"margin-top: 30px; text-align: center;\"\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/S361e930041534e559e33a3fbe55ca8d3K.webp?v=1751072185\" alt=\"The Airmatic Sentinel\" style=\"max-width:100%; margin: 8px 0;\" loading=\"lazy\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/S8d00f91178094d22ab13619ac5670272l.webp?v=1751072186\" alt=\"The Airmatic Sentinel\" style=\"max-width:100%; margin: 8px 0;\" loading=\"lazy\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/Se0f73fe1c97a4fb6abe9a23b9068d54dN.webp?v=1751072186\" alt=\"The Airmatic Sentinel\" style=\"max-width:100%; margin: 8px 0;\" loading=\"lazy\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/Sdfb31cdb61984ecd8aadc4bbd566de73U.webp?v=1751072186\" alt=\"The Airmatic Sentinel\" style=\"max-width:100%; margin: 8px 0;\" loading=\"lazy\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/Sd010a4e0c85d4f7d8b398442c18f31e4m.webp?v=1751072186\" alt=\"The Airmatic Sentinel\" style=\"max-width:100%; margin: 8px 0;\" loading=\"lazy\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/S1b58a3273980471286cdcaa401d6a814Z.webp?v=1751072185\" alt=\"The Airmatic Sentinel\" style=\"max-width:100%; margin: 8px 0;\" loading=\"lazy\"\u003e\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: What is included in the kit?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: The kit includes two rear air spring bags with their fittings, ready for installation. You reuse the factory air lines and mounting bolts unless they show wear, which is standard practice for this job.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How do I know my compressor is still good?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: If the compressor runs but the car keeps sinking, the springs are the usual culprit. If the compressor never runs or the car sits on the bump stops constantly, test the compressor and valve block before replacing the bags.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Will these fit a W251 with factory rear AC?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: Yes. The rear air spring position is independent of the climate equipment, and the kit mounts in the factory pockets on both chassis variants. If your car has a self-leveling option, the same spring geometry applies.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom: 15px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How do I bleed the system after fitting?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA: The Airmatic system self-levels through the compressor and valve block. After fitting, run the engine, let the suspension cycle through its height settings, and then perform a recalibration with a Mercedes-compatible scanner to store the new reference values.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\u003cscript type=\"application\/ld+json\"\u003e\n{\"@context\": \"https:\/\/schema.org\/\", \"@type\": \"Product\", \"name\": \"The Airmatic Sentinel | Mercedes R-Class W251 Rear Air Spring Kit\", \"image\": \"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/S361e930041534e559e33a3fbe55ca8d3K.webp?v=1751072185\", \"description\": \"A luxury car should not announce its age with a sagging corner. 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