While traveling on I-15 with my CLS63 AMG S in central Utah where the speed limit is 80 mph, I ran over an unavoidable object and suffered a front right tire flat. I used the “50 mph maximum space-saver spare” to limp home over 200 miles away and vowed to find a better solution to an inconvenient situation. (I did travel on the Interstate at around 60 mph with no problems but slowed down for any turns ‘cause, as suggested by my local tire dealer, the sidewalls of the spare are not designed to provide much cornering force. But it was not pleasant being passed by tractor trailer trucks going 20 mph faster.)

I frequently travel in Utah on I-15 and I-70 (where there is a sign “No Services Next 113 Miles”), and on Nevada’s Extraterrestrial Highway (Rt 375 — see photo) where it would be agony to travel any distance with the stock spare.


So it turns out that the wheel well in the trunk is large enough in diameter to accommodate a stock wheel and tire (255/35R19 and 285/30R19 — see photo) and an inflated space-saver spare. However, the well is not deep enough to accommodate these while allowing the trunk floor panel to lie flat.



The solution I was looking for was to find a wheel and tire combo that would be the correct circumference, offset and tread width while providing a reasonable match to the AMG wheels that I have. (Mercedes dealer price for the AMG wheel is $2450 each! Obviously not practical for a spare.)

Thankfully, I found the following — see 2 photos, side-by-side stock and spare wheels and tires:

Wheel from rimsntires.com: Verde Replicas V1174 CL65 Machined/Gray wheels
19x8.5 PCD 5x112 ET35, 6.1"BS $238.77

Tire from tirerack.com: 225/40ZR-19 Michelin Pilot Sport A/S 3 (Y-Speed Rated), $223.

Lug Bolts from NAPA: DOR 610-411, conical seat. (610-456 is too long for this wheel.)





By removing the Styrofoam pad under the stock spare, the trunk floor panel will lie flat. You'll need to carry a 19mm lug wrench with these lug bolts -- make sure you have the proper wrench with whatever bolts you use.

Note that the stock Mercedes lug bolts have a spherical seat. You need to make sure that the lug bolts you use match the wheel (in this case a conical seat) and that they protrude from the back of the wheel an amount similar to the stock bolts in the stock wheel (about 3/4 inch.) If in doubt on the seat shape, put a strip of Liquid Paper correction fluid on the bolt hole in the wheel and tighten down a spherical and conical bolt. The correct bolt will smear the entire strip of Liquid Paper; an incorrect bolt will leave most of it intact.

Then before driving, make sure that the bolts do not project too far into the hub such as to bind up anything. The bolts should turn into the hub about 8.5 + or - a half turn or so before seating into the wheel. More than that, then it may project too far into the hub. Less than than, there is not enough thread to provide the required strength.

I've run with this spare on both the front and rear with no problems. The circumference of the spare is within 0.5% of the stock front tire and 1.4% of the stock rear tire. It is not necessary to install a TMPS sensor. If you check the tire pressures while running the spare, the pressure will simply show up missing.

BTW — while you are checking things out, paint the hub and splash plate ‘cause the are going to rust and look ugly. See the before and after photos. Sand or steel wool any rust, use a light primer coat and then spray with some Dupli-Color High Heat Aluminum (DH 1606) — see before and after photos. Might as well have good looking hubs to go along with those good looking wheels! Hope this helps.

 

very nice, great solution, thanks for posting!

 

Great post with vital infos! Subscribed!