Just wanted to run this question by the members. I remember some conflicting info regard spare tires available for the M35. My M35X came with the donut spare but I believe I read somewhere that a full size spare was available as well when purchasing these cars new. If that's the case, that would mean the spare tire well in the trunk would accommodate a full size 18" wheel and tire. Can anyone confirm this or am I incorrect. Thanks.

I believe it shoud. I have no specific factual information on it but my deductive reasoning says it should. An M35X has an extra differential in the front, but nothing really too special in the rear. And I have a sport model with an extra electric motor in the back for rear tire turning which takes up more space. So if something with extra stuff inder the spare tire area can fit a full size 19" spare tire in the trunk than an M35x should as well.

The one difference between donut spare and full size in the trunk is that the trunk has a 2" layer of foam on the flow to space the floor up higher. If you dont have the foam spacer, a full size will stick up funny on the carpet.

I bought my 2006 M35x off the lot in late 2005. I reviewed the option list beforehand and believe I noted somewhere that the X models were equipped with a full size spare as standard with the X package, and as an option on RWD models. I cannot confirm this as factual, however.
That being said, while negotiating for the M35x I bought off the lot, I noted the spare was a space saver! I brought this to their attention, and the salesman told me some X's were coming in like that, and no problem for him to install a full size spare. Well, I bought the car...and the day I signed papers, he took the car around & parked it alongside a new sold, yet to be delivered M sport and told me the buyer wanted a space saver to optimize usage of trunk space. The salesman swapped out the tires & the modified shelf packaging needed to convert full spare to space saver.

I was happy...but since then I wondered if my X originally had a full size spare installed at the factory...and that the dealer swapped it out for a space saver!

I was nowhere in the position to be hanging out near an Infiniti dealership when these vehicles were new, but I have learned from this forum about the optional full size spare.
I also tested it myself, and the full size wheel+tire combo fits in the recess, it just pokes out upwards as well.

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When I saw the title of this thread, my mind immediately jumped to Steve_c. I remember us discussing this just the other day (6 years ago!) - spare-tire-longevity-t608959.html

Steve and Enigma are some of our active members who bought their Ms while the generation was still fresh. I'm glad you are both around here, and cheerfully sharing the knowledge you have.
Cheers! To more health and prosperity in your endeavors gentlemen.

Here's another interesting discussion regarding spare wheels - 06-m35-full-size-spare-t371622.html

I went to Discount Tire last week to have a new set on Continental’s installed. The tech said he thought the space saver spare was original and never used. He recommended it be replaced because of age and condition. It cost about $89 for the tire and mounting. I’m good with the new space saver as I always replace my tires well before their worn and I would probably not change it myself. AAA to the rescue.