I'm having serious handling issues with new Michelin Agilis HD Z 245/70R19.5 tires on my 2018 Winnebago Vista LX 27N. The RV now has 25k miles, and since switching from Goodyear tires, I'm experiencing terrible tail wag - especially when towing my 2024 Toyota Tacoma and in windy conditions.
I've tried multiple tire pressures (82 psi from door sticker, 110 psi from installer, up to 100 psi) but nothing resolves the side-to-side movement. I have several stability modifications installed (Rear Trac Bar, Aux Roadmaster Rear Swaybar, Front Roadmaster Swaybar, Koni FSD shocks), which previously helped with handling.
The movement feels like the towed truck is actually pushing the RV's rear side-to-side, making driving extremely uncomfortable. I'm within Michelin's 60-day/2500-mile buy-back period and want to understand why these tires are performing so differently from my previous set.
Could experienced RV owners help me diagnose what might be causing these handling problems?
Michelin RV tire handling problems often stem from incorrect tire pressure, load rating mismatches, or construction differences between tire brands. Most issues can be resolved through proper pressure adjustment, load distribution, or tire replacement with better-suited models.
SAFETY WARNING: The handling issues described involve dangerous driving conditions. Do not continue driving if conditions worsen and seek immediate professional assistance if unsafe conditions develop.
Your 2018 Winnebago Vista LX 27N is experiencing dangerous tail wag and handling issues specifically after switching from Goodyear tires to the new Michelin Agilis HD Z 245/70R19.5 tires. This appears to be a compatibility issue with certain RV chassis and the Michelin Agilis HD Z design. The tire's sidewall construction and tread pattern can create instability on some Class A motorhomes, especially when towing. Your symptoms - the side-to-side flex, wind sensitivity, and the feeling of your Tacoma pushing the RV around - are classic signs that these particular Michelins aren't suited for your specific chassis setup, despite your excellent suspension modifications.
The fact that you've tried multiple pressure settings with no improvement confirms this isn't a simple inflation issue. Your Roadmaster sway bars, Trac bar, and Koni FSD shocks should handle normal tire transitions, but they can't compensate for a fundamental tire design mismatch with your chassis dynamics.
The Michelin Agilis HD Z has a different sidewall construction and contact patch geometry compared to your previous Goodyear tires. While these Michelins excel on many RVs, they can create handling issues on certain Ford F53 chassis (which your Vista LX uses) due to how the tire's sidewall flexes under cornering forces and crosswinds. The tire's design may prioritize different characteristics than your previous tires, which works great for highway cruising but can create problems when combined with the higher center of gravity and wind sail effect of your Class A.
When towing your Tacoma, the additional vehicle weight and towing dynamics amplify any rear axle instability. The Michelin's sidewall construction may allow more lateral movement, which gets magnified through your RV's suspension geometry. Wind conditions make this worse because the tire's contact patch can't maintain consistent road contact when lateral forces increase. Your previous Goodyears likely had a stiffer sidewall construction that better matched your chassis requirements.
Even your excellent suspension modifications can't overcome a fundamental tire-to-chassis mismatch. The Roadmaster components are designed to control body roll and reduce sway, but they're working against a tire that's creating instability at the road surface level.
WARNING: Dangerous handling conditions require immediate attention. Do not continue driving in unsafe conditions. Consider stopping if conditions deteriorate further.
Since some dealers may offer buyback periods (which vary significantly by dealer and are not guaranteed), document everything immediately. Take photos of your tire wear patterns, write down specific driving conditions where problems occur, and keep receipts from your installation. Contact your tire dealer first thing Monday morning to initiate the return process - don't wait as this policy has strict time limits.
While preparing for the return, research replacement options specifically validated for Ford F53 chassis motorhomes according to manufacturer specifications. Consult with tire manufacturers and RV chassis specialists to identify the best options for your application in your 245/70R19.5 size. Consider tire models with stiffer sidewalls and better stability characteristics designed for Class A RVs.
Gather your vehicle documentation including GVWR, actual axle weights if you have them, and your current suspension modification details. This information will help your tire dealer recommend the best replacement and proper inflation pressures. Consider getting your RV weighed at a truck scale or CAT scale to establish proper tire pressure calculations based on actual load rather than door sticker recommendations.
Contact your Michelin dealer immediately to start the buyback process, emphasizing the dangerous handling characteristics and that the tires are creating unsafe driving conditions. Most dealers will accommodate this request quickly when safety is the primary concern. Document your conversation and get a return authorization number.
For replacement tires, consult with tire dealers and RV specialists to identify the correct tires for your model (verify with dealer) in 245/70R19.5. Research tires that are proven performers on Ford F53 chassis and will work well with your existing suspension modifications. Expect tire costs to vary based on your location and chosen brand.
When installing new tires, start with inflation pressures calculated using the standard formula (Load ÷ Load Rating × Max PSI) based on your actual axle weights and manufacturer specifications rather than door sticker recommendations. Have the installer check wheel alignment and suspension components during installation, torquing all components to manufacturer specifications.
Test drive without the trailer first to establish baseline handling, then add the Tacoma for towing tests. Make gradual adjustments to tire pressure based on handling characteristics and manufacturer guidelines, but don't exceed maximum tire pressure ratings or go below minimum load requirements.
If Michelin refuses the buyback or if new tires don't completely resolve handling issues, you'll need professional chassis evaluation. A qualified RV service center should check your suspension components, steering box adjustment, and wheel alignment. Even small changes in these areas can be magnified when combined with tire characteristics.
Consider professional weighing and tire pressure calculation services if you continue having handling issues with replacement tires. Many RV dealers offer comprehensive chassis evaluation that includes individual wheel position weights and customized tire pressure recommendations based on manufacturer specifications.
If handling problems persist across different tire brands, investigate whether your suspension modifications need adjustment or if additional chassis bracing is required. Some Vista LX owners have found that adding rear track bars or upgrading to heavy-duty rear sway bars helps with towing stability, though your existing Roadmaster setup should be adequate for most conditions.
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