E70 Spare Tire

[spawn1980]

I have staggered wheels on my 2012 x5 My front is 275-40-20, my back is 315-35-20. I was told (Tire shop) I should use the same size as my front for a spare to work with the front and back but i'm not sure how true that is. What do you guys think since the x5 doesn't come with a spare

[Qsilver7]

If your X was originally optioned with run flats...you don't have a spare. And if it did come with a spare (with room below the cargo floor for it)...it would [n]not[/b] have been a 20" wheel/tire combo. BMW stopped using "matching" spare wheels around early Y2K...BMW usually puts a smaller 17"/18" full size spare tire even if the optioned wheels were 19" or 20". See your owners manual or the tire pressure chart on your driver's door/door jamb...it will reveal what size spare is recommended. Usually anything larger that the smallest recommended tire size will be too large to allow the cargo floor to lay correctly in place.

If you go to one of the online part databases (like www.realoem.com or www.bmwfans.info or www.etk.cc ) and enter your VIN and go to the WHEEL diagrams...you'll see what size spares are available for your vehicle. If not a full size spare...it will probably be an 18" or 19" "donut" spare.

FYI...if you understand "plus 1 sizing"...then you will understand how a 20" wheel/tire combo can have the same overall diameter/circumference as the other recommended tire sizes on the tire inflation chart.

[spawn1980]

If your X was originally optioned with run flats...you don't have a spare. And if it did come with a spare (with room below the cargo floor for it)...it would [n]not[/b] have been a 20" wheel/tire combo. BMW stopped using "matching" spare wheels around early Y2K...BMW usually puts a smaller 17"/18" full size spare tire even if the optioned wheels were 19" or 20". See your owners manual or the tire pressure chart on your driver's door/door jamb...it will reveal what size spare is recommended. Usually anything larger that the smallest recommended tire size will be too large to allow the cargo floor to lay correctly in place.

If you go to one of the online part databases (like www.realoem.com or www.bmwfans.info or www.etk.cc ) and enter your VIN and go to the WHEEL diagrams...you'll see what size spares are available for your vehicle. If not a full size spare...it will probably be an 18" or 19" "donut" spare.

My plan was to make a spare tire with a random same bolt 20" wheel and a tire. I never thought about the cargo floor measurement. The link shows "5JX18 ET:14" Can I use a 18" spare with 20"? I know its temporary but is it safe?

[Cooki3Monster]

Fwiw, the spare in my x5 from factory was a 15” rim with the OD being ever so slightly more than my 20” Wheels. I can’t recall clearly, but all wheel/tire options may have come out to roughly the same outside diameter, I may be wrong here. it doesn’t matter what you have as long as the stud pattern and od match. There is also the issue of different tires and contact and drag that is ok for short distances only. It should be safe, but only for short use, I read that if the OD is out by like 10mm it can cause issues with the transfer case and xdrive system with extended use. In a pinch this can be assisted by removing fuse 92(if my memory serves me well) to disable the transfer case. Be aware it also turns off dsc and traction control, but not abs.


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[Qsilver7]

...Can I use a 18" spare with 20"? I know its temporary but is it safe?[/I]

Every tire size listed on your tire pressure inflation label (on the door/door jamb & owners manual) has the same overall diameter/circumference...even though they are not the same size (18",19",20", etc). And as mentioned in my previous post...BMW doesn't even give you the same size spare if your BMW is optioned with wheels/tires larger than the smallest size that will fit over the brakes.

FYI...if you understand "plus 1 sizing"...then you will understand how a 20" wheel/tire combo can have the same overall diameter/circumference as the other recommended tire sizes on the tire inflation chart.

[peter2772000]

On my GC SRT with 20's, if you used the spare, you had to remove the rear tire and put it in front, then use the spare on the rear. Ridiculous, pulled that sucker outta there in milliseconds.
I stopped carrying spares on all my vehicles years ago (with the exception of my FJ Cruiser, that big fat tire looks good up there LOL). FixFlat juice, air compressor and AAA if ever needed (so far, never needed either). Oh, and tons of storage room now.

[spawn1980]

I called bmw they said its not a good idea to use a 18” spare with 20” because it would cause issues the computer wouldn’t know whats going on and run the wheels at different speed then give error lights. He also said maybe if the you can get a 18” with the same circumstance it would work. I’ve never heard of a 18” with the same radius as a 20” even if they did I would need it to fit in my cargo floor.

[Qsilver7]

... He also said maybe if the you can get a 18” with the same circumstance it would work. I’ve never heard of a 18” with the same radius as a 20” even if they did I would need it to fit in my cargo floor.

There is no "maybe"...its fact...and BMW has done it/did it for a long time. Before BMW went to runflat tires...starting around 2002/2003 (at least in the US market)....BMW started using the smallest size tire as a spare regardless of what size wheels/tires were mounted...as long as it fit over the brakes. For the some of the "sport" models that had larger brakes than the other models in the platform...the spare might be larger than the other models...but still smaller than the wheels/tires usually mounted on the vehicle.

BTW...all of the BMW recommended tires sizes in the owners manual and on the door's tire inflation chart have the same overall diameter/circumference (wheel & tire combined). So yes, as long as an 18" wheel fits over the vehicle's brakes...you can mount an 18" spare wheel/tire as long as the tire's specs are within 3% (+/-) the 19", 20", 21", etc wheel tire combo you have mounted.

And how would you explain the compact 19" spare?

For example, all of the tires listed in the owners manual have the same overall rolling diameter/circumference (within the 3% (+/-) range)...the same would apply to your e70 & 5 series:

[jclausen]

When BMWs had spares and you had staggered sizes the spare was always the front tire size

[Qsilver7]

... He also said maybe if the you can get a 18” with the same circumstance it would work. I’ve never heard of a 18” with the same radius as a 20” even if they did I would need it to fit in my cargo floor.

There is no "maybe"...its fact...and BMW has done it/did it for a long time. Just google for a simple "tire size calculator" then compare the 18/19/20/21 each tires listed in the owners manual or driver's door jamb and you'll see that the overall rolling diameter/circumference listed will ALL be within 3% (+/-) of each other.

Before BMW went to runflat tires...starting around 2002/2003 (at least in the US market)....BMW started using the smallest size tire as a spare regardless of what size wheels/tires were mounted...as long as it fit over the brakes. For the some of the "sport" models that had larger brakes than the other models in the platform...the spare might be larger than the other models...but still smaller than the wheels/tires usually mounted on the vehicle.

BTW...all of the BMW recommended tires sizes in the owners manual and on the door's tire inflation chart have the same overall diameter/circumference (wheel & tire combined). So yes, as long as an 18" wheel fits over the vehicle's brakes...you can mount an 18" spare wheel/tire as long as the tire's specs are within 3% (+/-) the 19", 20", 21", etc wheel tire combo you have mounted.

And how would you explain the compact 19" spare?

For example, all of the tires listed in the owners manual have the same overall rolling diameter/circumference (within the 3% (+/-) range)...the same would apply to your e70 & 5 series:

{from 2008 e70 X5 owners manual}




{from 2006 e53 X5 owners manual}

[spawn1980]

I guess the 18” will be fine if I get a flat and I can use it on the front or back

[Qsilver7]

I guess the 18” will be fine if I get a flat and I can use it on the front or back

I think ya got it, now. Yes, an 18" wheel with a 255/55/18 tire mounted will work as a spare if you have 19, 20, 21 inch BMW e70 wheels.

[spawn1980]

Yes, an 18" wheel with a 255/55/18 tire mounted will work as a spare if you have 19, 20, 21 inch BMW e70 wheels.

Ok so I can use the 255/55/18 with my front and back 275-40-20, 315-35-20

[spawn1980]

If the answer above is yes then this should work
https://www.ebay.com/itm/07-08-09-10...8AAOSwAk9ZpXaS

[Qsilver7]

Ok so I can use the 255/55/18 with my front and back 275-40-20, 315-35-20

Yes. If you input the 18" and 20" tire specs into a tire size calculator...you will see that they are within the 3% (+/-) allowable range. On my e53...I have 275/40/20 (f) & 315/35/20 (r) tires mounted on 20" Style 87 wheels...and my spare is a 17" Style 57 BMW wheel with a 235/65/17 tire:

Example below of a tire size calculator that shows the 20" tires you mention are equivalent to a 255/55/18 tire within 1%:

[spawn1980]

Yes. If you input the 18" and 20" tire specs into a tire size calculator...you will see that they are within the 3% (+/-) allowable range. On my e53...I have 275/40/20 (f) & 315/35/20 (r) tires mounted on 20" Style 87 wheels...and my spare is a 17" Style 57 BMW wheel with a 235/65/17 tire:

Example below of a tire size calculator that shows the 20" tires you mention are equivalent to a 255/55/18 tire within 1%:

I thank you