Anyone have an opinion on removing the spare tire for weight savings for acceleration or does the tire weight add to helping the car with traction? I think about this from time to time.

 

For a daily driver you would not be able to tell a difference. 50lb / 4000lb curb weight is 1.25%. If you are going to the race track, sure take it out. Additionally, many manufacturers incorporated the spare tire as part of the crumple zone to absorb energy in an impact.

There are other ways to save weight but its cost vs gain. A full custom exhaust, lithium battery, lighter wheels, 2 piece lightweight brake rotors, etc... At the end of the day the XJ is a full size luxury sedan.

 

XJR = "Don't Worry, Be Happy".
Nevertheless, 1% saving is 1% if it makes you happy, at zero cost. 1% of total weight just for the spare seemed like quite a bit to me!

My A180 has no spare and no jack. Although it has run-flats and "free" roadside assistance.
My Honda Insight had no spare just a squirty bottle.
Last time I had to change a tyre on the roadside was around 1995.
My XJ Japanese Import has a "space saver", Swap ya!

Unless you wheel spin, the weight of the spare doesn't matter? And then, 1% or 2% presumably.
But as he said ^, I doubt you'll tell the difference.

 

Expect at least a 20% speed improvement ?

 

I wouldn't go anywhere without a spare. I've had to use a spare WAY too many times. And its never just a nail that can be sealed with a can of goo. I've relatives with cheaper cars that came without spares. I'm always on my way again after swapping the spare in 15 minutes, 20 minutes tops. They're always calling the tow truck and back on their way after getting a new tire TOMORROW... at the EARLIEST!

Now back in my younger years when I was participating in official sanctioned events, the solution was simple. We took out our spare tire, along with our tools and supplies plus anything else unnecessary that could be easily removed under the rules and left it all in a pile in the paddocks until the end of the event. And I don't think it helped at all because I still came in last.

 

Could be you have too much time to think

 

I've read that spares were eliminated by manufactures to squeeze more miles out of every gallon of fuel: Losing 40-50 lbs. of weight helps to increase fuel economy oh so slightly. It also increases automakers’ profits because they don’t have to pay for those parts. Got a midnight call from a family member whose late model Cadillac had a blow out an hour from home. He had no spare but a 12VDC pump of no use because the sidewall had a hole in it. Had the car flat-bedded to a tire shop the next day, etc. Checked wife's new Jeep Cherokee. Same set up. Ordered her a spare tire kit with a donut tire assembly (wheel, tire and valve stem), jack, wrench, and hardware. She feels better and by extension, I feel better. I also use a life vest when kayaking.

 

What if your life vest got a puncture? Oh sorry, too much time to think ​​​​​​​

 

you're probably right, but also like to add something to a board that is stale some of the time.

 

I always take the spare tire out of my cars. Just put a box of tire foam in the boot instead.
As I live in a cold climate the spare tire is useless 50% of the time due to frost and snow anyways.

 

Unless there is a cut or hole in the sidewall...then the tire snot is worthless.

 

My wife picked up a new Audi Q5. Those Germans think of everything.
The space saver tired is deflated. Comes with air compressor and can of snot. Guess you can add your snot and air tire back up. Or remover spare and inflate to use. Assume the air pump will deflate to allow stowing back in the trunk.
But would never remove the spare, even with the spare tire pressure warnings I get.

 

I guess it kind of depends on where you live and how easy it is to get a flatbed to haul you home/ to the nearest garage.

The tyre foam have saved me a lot of times

 

I drove my Honda Insight 25km across town with a "blown tyre". Hardly even knew, wasn't being chased by the cops or anything. Wrecked the tyre of course.

The moral of the story is that you should all sell your Jaguars and buy Honda Insights...
No no, the moral of that story is that an Insight tyre was $100 who cares. whereas our Jag tyres are $500 or something.

 

The car's too heavy to make a difference and like others mentioned, there are better ways to save weight (lighter wheels/brakes will be much more noticeable). I haven't had a spare in my other cars for a few years so now that I picked up the XJR, I'm definitely keeping it.

How often do people replace their tire due to age? Usually you don't want to drive on tires older than 5 years but with seldom used spares that rarely see any sun, the integrity of the rubber shouldn't be compromised. I checked mine and it's still the original from 2004.

 

There is a tire shop just a few blocks from my house that I pass almost daily. I frequently see cars driving in on flat tires, having driven who knows how far to get there. Nevermind the cost of the tire. What does a Jaguar wheel cost? Heck, the wheel for your Honda Insight is probably over $300. I was in there one day and happened to overhear their conversation with one such customer. They tell the guy that they can't install a new tire because he damaged his rim too bad by driving on it. They offered to order a wheel and install it the next day but that was going to be too expensive so he got back in his car and drove away. And what's worse, I watched him enter the ramp to the freeway with sparks flying.

There's other threads on the subject of tire expiration dates but your old spare tire is probably perfectly safe to use, particularly when its just temporary or if you are actually going to heed the max speed warning on the space-saver donut. However, you may still not be able to use it. One more thing that I bet a lot of those people driving on flat tires into the tire shop above did was they forgot to regularly check to see if their spare tire had enough air in it.

 

Driving my Honda Insight across town on a flat tyre did not damage the rim.
You see, I'm a sensible guy. This does not explain why I have a Jag...

In the end, and as already said, I have not had a roadside change since 1995. It's really hard to coordinate bum-sticking-out with the passing traffic. (I shouldn't joke, someone got killed here relatively recently doing just that)
My runaround Merc has run-flats. And all my cars have roadside assistance as part of the insurance.

My Jag has a spare tyre, plus a compressor when I do a trip. Just in case. But the horror stories you read above are extremely rare, IMHO.

 

I always keep about 10 psi higher than the normal running pressure in the spare as I only check it every 6 months or so, or when I remember. One of my previous cars (I think it may have been a Subaru) had the spare wheel mounted "upsidedown" so you have to take the wheel out of the boot to access the valve, "what were they thinking?"

 

Could be there was a full sized spare, instead of a space saver..
Had a full size one in both my Honda's.
But to fasten things down, up side down was required.

 

If you have a full size spare you are very lucky. If you have a donut spare you are still lucky. If you have no spare for any reason you are sunk. Even if you call the auto club to change the wheel, you should be on your way in an hour. Without a spare you'll have to be flatbed towed to a tire shop and settle for whatever tire they have got on hand, or wait for them to order you one. Many hours will be spent waiting and you'll likely miss a lot of time from your job. My Daughter in Law just got a flat with no spare, Besides a lot of time standing on the shoulder of the freeway, she got dropped in a parking lot by the CHP Freeway Patrol truck, then she had to wait for another car carrier to tow the car to a tire shop. Half the day was wasted.