Tire & Wheel Size Calculator
Thread Starter
MBWorld Fanatic!
Joined: Oct 2019
Posts: 5,161
Likes: 1,772
From: Colorado
G550
Tire & Wheel Size Calculator
For everyone thinking about tire and/or wheel upgrades, there's a helpful graphic comparison calculator at https://rimsntires.com/specspro.jsp It's worth checking out even if you've already made the change.
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
Likes: 133
From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
For everyone thinking about tire and/or wheel upgrades, there's a helpful graphic comparison calculator at https://rimsntires.com/specspro.jsp It's worth checking out even if you've already made the change.
Senior Member
Joined: May 2017
Posts: 459
Likes: 301
From: Plano, Texas
2012 G550 - Capri Blue Metallic
Great site, I had stumbled across it before but forgot to bookmark it.... thanks!
So general question for everyone on their tires... do you rotate all 5, or just the 4 in use?
I had planned to rotate all 5, but my tire guy reminded me that the spare didn't have a TPS installed so I've ended up only rotating the 4.
Which made me think about my next set of tires. I plan on going up to 325/65-18s which will have a diameter of 34.6" and weigh 76lbs (since I plan on the BFG KM3s). My current 305/65-18s have a diameter of 33.6" and weigh 62lbs, a substantial 14lb weight gain.
I'm not so much worried about rotating mass as I am about the spare mount having to support an extra 14lbs. If I continue to only rotate the 4 tires in use, why not go with a lighter tire as a spare, with the same diameter?
For example, if I go with the KM3s, I could feasibly buy a single Atturo Trail Blade X/T spare tire in 18" size, with the exact same diameter of 34.6" and it will only weigh 64lbs, potentially reducing 12lbs of weight on the spare tire holder.
I would assume that as long as the spare is the exact same diameter as the other tires, there will be no transfer case or drivetrain issues if I need to use it. Kind of like having a 'mini-spare'.
Oh, and I save some $$ in the process....
So general question for everyone on their tires... do you rotate all 5, or just the 4 in use?
I had planned to rotate all 5, but my tire guy reminded me that the spare didn't have a TPS installed so I've ended up only rotating the 4.
Which made me think about my next set of tires. I plan on going up to 325/65-18s which will have a diameter of 34.6" and weigh 76lbs (since I plan on the BFG KM3s). My current 305/65-18s have a diameter of 33.6" and weigh 62lbs, a substantial 14lb weight gain.
I'm not so much worried about rotating mass as I am about the spare mount having to support an extra 14lbs. If I continue to only rotate the 4 tires in use, why not go with a lighter tire as a spare, with the same diameter?
For example, if I go with the KM3s, I could feasibly buy a single Atturo Trail Blade X/T spare tire in 18" size, with the exact same diameter of 34.6" and it will only weigh 64lbs, potentially reducing 12lbs of weight on the spare tire holder.
I would assume that as long as the spare is the exact same diameter as the other tires, there will be no transfer case or drivetrain issues if I need to use it. Kind of like having a 'mini-spare'.
Oh, and I save some $$ in the process....
Last edited by Limey Hooligan; Oct 31, 2020 at 10:09 AM.
Super Member
Joined: Aug 2020
Posts: 783
Likes: 266
G63, G65
Great site, I had stumbled across it before but forgot to bookmark it.... thanks!
So general question for everyone on their tires... do you rotate all 5, or just the 4 in use?
I had planned to rotate all 5, but my tire guy reminded me that the spare didn't have a TPS installed so I've ended up only rotating the 4.
Which made me think about my next set of tires. I plan on going up to 325/65-18s which will have a diameter of 34.6" and weigh 76lbs (since I plan on the BFG KM3s). My current 305/65-18s have a diameter of 33.6" and weigh 62lbs, a substantial 14lb weight gain.
I'm not so much worried about rotating mass as I am about the spare mount having to support an extra 14lbs. If I continue to only rotate the 4 tires in use, why not go with a lighter tire as a spare, with the same diameter?
For example, if I go with the KM3s, I could feasibly buy a single Atturo Trail Blade X/T spare tire in 18" size, with the exact same diameter of 34.6" and it will only weigh 64lbs, potentially reducing 12lbs of weight on the spare tire holder.
I would assume that as long as the spare is the exact same diameter as the other tires, there will be no transfer case or drivetrain issues if I need to use it. Kind of like having a 'mini-spare'.
Oh, and I save some $$ in the process....
So general question for everyone on their tires... do you rotate all 5, or just the 4 in use?
I had planned to rotate all 5, but my tire guy reminded me that the spare didn't have a TPS installed so I've ended up only rotating the 4.
Which made me think about my next set of tires. I plan on going up to 325/65-18s which will have a diameter of 34.6" and weigh 76lbs (since I plan on the BFG KM3s). My current 305/65-18s have a diameter of 33.6" and weigh 62lbs, a substantial 14lb weight gain.
I'm not so much worried about rotating mass as I am about the spare mount having to support an extra 14lbs. If I continue to only rotate the 4 tires in use, why not go with a lighter tire as a spare, with the same diameter?
For example, if I go with the KM3s, I could feasibly buy a single Atturo Trail Blade X/T spare tire in 18" size, with the exact same diameter of 34.6" and it will only weigh 64lbs, potentially reducing 12lbs of weight on the spare tire holder.
I would assume that as long as the spare is the exact same diameter as the other tires, there will be no transfer case or drivetrain issues if I need to use it. Kind of like having a 'mini-spare'.
Oh, and I save some $$ in the process....
Also, if the Artturo weighs 12lbs less it has to be sacrificing something, somewhere. I'd guess in sidewall durability, which is not something you want to sacrifice since you actually off road.
Thread Starter
MBWorld Fanatic!
Joined: Oct 2019
Posts: 5,161
Likes: 1,772
From: Colorado
G550
Great site, I had stumbled across it before but forgot to bookmark it.... thanks!
So general question for everyone on their tires... do you rotate all 5, or just the 4 in use?
I had planned to rotate all 5, but my tire guy reminded me that the spare didn't have a TPS installed so I've ended up only rotating the 4.
Which made me think about my next set of tires. I plan on going up to 325/65-18s which will have a diameter of 34.6" and weigh 76lbs (since I plan on the BFG KM3s). My current 305/65-18s have a diameter of 33.6" and weigh 62lbs, a substantial 14lb weight gain.
I'm not so much worried about rotating mass as I am about the spare mount having to support an extra 14lbs. If I continue to only rotate the 4 tires in use, why not go with a lighter tire as a spare, with the same diameter?
For example, if I go with the KM3s, I could feasibly buy a single Atturo Trail Blade X/T spare tire in 18" size, with the exact same diameter of 34.6" and it will only weigh 64lbs, potentially reducing 12lbs of weight on the spare tire holder.
I would assume that as long as the spare is the exact same diameter as the other tires, there will be no transfer case or drivetrain issues if I need to use it. Kind of like having a 'mini-spare'.
Oh, and I save some $$ in the process....
So general question for everyone on their tires... do you rotate all 5, or just the 4 in use?
I had planned to rotate all 5, but my tire guy reminded me that the spare didn't have a TPS installed so I've ended up only rotating the 4.
Which made me think about my next set of tires. I plan on going up to 325/65-18s which will have a diameter of 34.6" and weigh 76lbs (since I plan on the BFG KM3s). My current 305/65-18s have a diameter of 33.6" and weigh 62lbs, a substantial 14lb weight gain.
I'm not so much worried about rotating mass as I am about the spare mount having to support an extra 14lbs. If I continue to only rotate the 4 tires in use, why not go with a lighter tire as a spare, with the same diameter?
For example, if I go with the KM3s, I could feasibly buy a single Atturo Trail Blade X/T spare tire in 18" size, with the exact same diameter of 34.6" and it will only weigh 64lbs, potentially reducing 12lbs of weight on the spare tire holder.
I would assume that as long as the spare is the exact same diameter as the other tires, there will be no transfer case or drivetrain issues if I need to use it. Kind of like having a 'mini-spare'.
Oh, and I save some $$ in the process....
If you don't plan on using a reverse-mount extension bracket as other have done, 14 lbs extra on the OE bracket can't be much worse than hanging the OE spare weight further out 8" or so.
I mounted a matching 275/55R20 spare when I changed out the OE tires. The spare cover wasn't even big enough to cover the OE 275/50R20, so MB slapped on a 265/50R20 so it would fit, and still called it a "full-size spare", but then stuck a "Max 45 mph" sticker on it. So the OE spare couldn't be used in a 5-tire rotation. Glad to be rid of the OE Pirelli's and the OE Continental spare.
I've acquired a new spare tire cover from Boomerang, and will post pics and info when it's installed.
My spare wheel had a TPMS installed on it, although it's not included in the monitoring system -- only when it gets mounted. I'm not sure, but the MB alloy wheels are machined for TPMS sensors and not conventional valve stems. Have your tire guy check your spare again. He might have assumed that since it doesn't show up on the instrument panel, it's not included on the wheel. Even if you have to add one, it's only about $40.
