full spare in the trunk?
Full size spare (OEM 245/40-18 on 18x8.5") does fit, but it lifts floor cover about 1/2".
I found out that narrower than stock, but still full size tires - 215/50-17, 215/45-18, 225/50-17 or 225/45-18 - all fit while lid ramains flat. On top of that, with 215 width tires, even intermediate cover (between main lid and spare tire) still fits. The only dowside is that a separate, narrower than stock (7.5" or 8") wheel, will be required. I sold all my temporary spare wheel/tire assemblies and replaced them all with full size wheel/tire (both narrower than stock, but still full size) from TireRack.
I found out that narrower than stock, but still full size tires - 215/50-17, 215/45-18, 225/50-17 or 225/45-18 - all fit while lid ramains flat. On top of that, with 215 width tires, even intermediate cover (between main lid and spare tire) still fits. The only dowside is that a separate, narrower than stock (7.5" or 8") wheel, will be required. I sold all my temporary spare wheel/tire assemblies and replaced them all with full size wheel/tire (both narrower than stock, but still full size) from TireRack.
I was able to fit a full size spare in my 2010 E550 (245/40-18) without lifting up trunk floor cover at all. I just had to remove the black styrofoam liner in floor of trunk (under the temporary spare), so that full size spare is on the bottom of the well. Much better to have in emergency than a temporary...back to running full speed!
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Super Member




Joined: Jul 2015
Posts: 795
Likes: 187
From: San Diego, CA
2016 E350 Sport; Mom Wrecked the 2008 E350; sold the 2002 C320
I added a full size spare (BRABUS Monoblock R 18x8.5) complete with TPMS. I went with the regular tire size (245/40/18). When I had the tire mounted, I asked them to program the TPMS to the car but the shop told me that the TPMS system can only read 4 sensors, so no need to program it until I use it.
I got a flat yesterday and I'm happy to report that after driving a couple of minutes on the spare, the low tire warning turned off by itself, so it definitely read the new sensor with no programming needed!
BTW I also removed the Styrofoam liner and the cover is only raised a tiny hair - barely noticeable.
All said, I'm glad I did it. definitely beats driving on a donut spare - especially in the rain.
I got a flat yesterday and I'm happy to report that after driving a couple of minutes on the spare, the low tire warning turned off by itself, so it definitely read the new sensor with no programming needed!
BTW I also removed the Styrofoam liner and the cover is only raised a tiny hair - barely noticeable.
All said, I'm glad I did it. definitely beats driving on a donut spare - especially in the rain.
MBWorld Fanatic!




Joined: Jan 2009
Posts: 9,222
Likes: 1,797
From: V E G A S
1922 Ford Model T / no OBD
Yeah. MB has directional antennas, who will detect sensor position. On bad side, it might take long time, so when you start the morning with flat tire, by the time TPMS will become active, your tire might be in shreads.
On my dually Ford I had to buy special tool to reposition the sensors in memory when dealer screw it up.
But then I have pressure reading on instant.
Why don't manufacturers include spare, beats me? I am rare one, who checks spare tire pressure every year, and unused rubber loose the pressure much faster than used one.
So I assume most of the owners, even if they will change the wheel, might find it low on air afterall.
On my dually Ford I had to buy special tool to reposition the sensors in memory when dealer screw it up.
But then I have pressure reading on instant.
Why don't manufacturers include spare, beats me? I am rare one, who checks spare tire pressure every year, and unused rubber loose the pressure much faster than used one.
So I assume most of the owners, even if they will change the wheel, might find it low on air afterall.
Last edited by kajtek1; Mar 26, 2020 at 01:26 PM.
Full size spare (OEM 245/40-18 on 18x8.5") does fit, but it lifts floor cover about 1/2".
I found out that narrower than stock, but still full size tires - 215/50-17, 215/45-18, 225/50-17 or 225/45-18 - all fit while lid ramains flat. On top of that, with 215 width tires, even intermediate cover (between main lid and spare tire) still fits. The only dowside is that a separate, narrower than stock (7.5" or 8") wheel, will be required. I sold all my temporary spare wheel/tire assemblies and replaced them all with full size wheel/tire (both narrower than stock, but still full size) from TireRack.
I found out that narrower than stock, but still full size tires - 215/50-17, 215/45-18, 225/50-17 or 225/45-18 - all fit while lid ramains flat. On top of that, with 215 width tires, even intermediate cover (between main lid and spare tire) still fits. The only dowside is that a separate, narrower than stock (7.5" or 8") wheel, will be required. I sold all my temporary spare wheel/tire assemblies and replaced them all with full size wheel/tire (both narrower than stock, but still full size) from TireRack.
Yeah, I know this is a very old thread, but I have to ask:
What aspect ratio in the 215 tire gave you the correct outside dimension for the wheel/tire setup, 70, 75, 80, more?
Thank you!
Last edited by CapeFearElvis; Feb 13, 2026 at 06:06 PM.





