I bought a 97 E420 with 52K miles a few months ago. Now at 60K Ireally need to replace the OE Michelin MXV4 Plustires. I've read some comments by other MB 420/320 owners who love the Michelin Hydoedge for its outstanding traction.
I notice there are a few differences in the specs: The Hydo's a T speed-rated tire (118 mph) compared to the H rating for the original. The Hydo's rated for 1356 lbs per tire, vs the 1433 for the original. Most of all, the Hydo's 25.1 inch diameter makes 829 revs per mi, vs the 25.5 inch and 829 revs for the MXV4.
I assume the load and speed differences won't matter for my very "normal" driving habits, but I wonder whether the small diff inrevs per mile will affect any of the monitoring/computingaspects of the car and alter itsperformace. Is the 2% difference there just too little to matter, or shouldI stay with the OE tire, in spite of its terrible traction?

 

I don't think you will notice the difference in tire size at all.
What are the treadwerar ratings for each tire?

Blue

 

Thanks.
According to the specs at tirerack.com, the OE MXV4 Plus has no stated treadlife warranty; the HydroEdge has a 90,000 mile tread warranty. In the ongoing online survey atthat website,the OE tires were rated a 7.2 on treadwear and the Hydos got a 9.0 in the survey (based on about 1500 and 800 responses, respectively).

 

Hi,
If your tyre sare nearly worn out "grip" will have significantly worsened from new.

My view is stay with an OE fitted/recommended tyre.

Car manufacturers spend much time and money determining the best tyre choice based on tyre performance which is a compromise.

Best wear rate, ride, steering response, noise etc. BUT you can't have the BEST in every characteristic. Simplistically best wear is contra to best grip. Best steering response contra to best ride etc.

If you drive "normally" I'm surprised that you have a traction problem (except possibly in the wet on flooded roads / smooth tarmac.).

Go with an OE fit tyre different to what is already fitted, if you don't like the current tyre.

OK, other makes will fit but for instance if diameter = distance / rev will impact speedometer accuracy. Diameter also alters clearance to bodywork, Load / speed rating is self explanatory. etc etc.

Yes your proposal SHOULD be OK but any change in gearing (ie tyre size) will impact your transmission (and to some extent engine) performance map shift points etc.