245 -45-20 good size for my X5
 

Hi All, I have a 05 X5 and I'm looking to upgrade with a cheap and cheerful set.

i have an opportunity to get this size set that came off a Cadillac CTS for $1000.

Will they be to small and look stupid.

yes I checked the specs and they are 5x120 with 14mm lug diameter and 38 offset

Thanks

The speedo already reads a few mph faster then actual speed, these tires will make that condition worse (that size requires an additional 10+ revs per mile (approximation) then the OEM sizes). I would bet they also have a lower load rating then the OEM rubber. Not a good choice.

Those tyre sizes are spot on with OE 20" tyre set up...They match exactly ,same rolling diametre and speedo reading,so you will have no problems with that.
With that 38 offset,you may need some spacers to push the tyres out.
Without knowing the wheel width is difficult to tell if the tyres will be too close to your suspension.This maybe the only issue!
Only thing I see is those tyres being too skinny for the X5 ,but will be fine especially as the 17" OE tyres are 235!

Really more revs per mile, how can that be I'm running 17's right now? As far as load the vehicles are of equal weight

The 17 is only the rim diameter, it does not define tire diameter. Different section width/aspect ratios will change the overall diameter of the rim/tire assembly. The standard E53 Sport Pkg W/18in rims came with a 255-55-18 tire, it's 29 inches tall and has a 105V load/speed rating (max load is 2,039 lbs & max speed is 149 mph), these rotate approx. 718 times per mile.
The 245-45 on a 20in rim is .3 in shorter (28.7 inches) and rotate approx 727 times per mile (9 more revs then noted above). Most all tires in this size will have a load rating BELOW 100, a 99 load rating is only 1709 lbs (thats 330 lbs LESS per tire, times 4 is almost a 3/4 ton reduction in the load limit). If you are using the vehicle as designed (read, hauling, trailering), or anyone who also uses the vehicle intends to use as such, you could overload the tires and/or rims (you need to see what the gross vehicle weight and max trailer tongue weight is on the Cadillac). I will bet the X5 has much higher weights then the Caddy.

Oh, as for your "both weigh the same" statement, CTS weighs 3568lbs, X5 weighs 4828. The two are not even CLOSE.

:iagree:

I'm still trying to figure out how this proposed idea would be considered an upgrade considering the wheel/tire setup is not even suited for an x5. If you want something different, i'm sure you can find a larger OEM wheel setup for a little more than what you're about to pay for these wheels.

These wheels will make your X look......Its a mistake all together. Aside from the appearance, it'll drive horribly and be unsafe on public roads.

Thanks for your input guys but I don't get it.

Currently my oem's are 17 with 235/65's, they measure 28 inches total diameter.

I like the style and colour of these rims and rubber and they are 20's which is why I thought they would male my truck look better.

Are you saying that overall the set up will be smaller Looking in the wheel well?

My wheel/tire upgrade (OE was 255-55-18) consisted of bulletproof FORGED BBS 8.5 & 9.5 X 19 wheels (due to the fact that if you go any larger, the space between the rotors/calipers and rims looks retarded) the gap with the 19s is just over one inch, go bigger and you will want bigger rotors/calipers. Went with the Hankook Ventus AS (255-50 F & 285-45 R) tires because of the 107W rating (2149 lbs and 168 mph max speed), these tires are rated in EXCESS of the OE sport wheel/tire package. These are also 29.1 inches tall and therefore rotate approx 5 FEWER revs per mile, at full tread these tires corrected my speedo error (100mph on odo shows 101 on GPS). It's a BMW....FORM FOLLOWS FUNCTION.....if you mod, make it BETTER!!!

Where the hell are you getting your info from???? The Michelin Energy Green X tires that came from BMW on that truck measure 29.1 inches in diameter!!!!!

I bought the truck used in 09, it's an 05 3.0 and has GY ultra grips 235 65 17 and I just took a measuring tape to them and the are 28 inches tall.

So I guess your saying that the previos owner screwed up when replacing he tires