: 20in wheels question on STS4



jjsocrazy
10-08-07, 10:14 PM
Here is a question that I still haven't had answered quite correctly. I have a 2007 Cadillac STS-4 V6. I want to upgrade my rims very bad and I love the look of 20's on the car. My friend has a 2006 version of my car but RWD w/ 20's and I really would like to do that.

I spoke to my father who works for Cadillac as a Salesmanager and he told me that even 18in rims on my car would not be good because of the suspension. I think he got confused because the 18's you can get are 6 lug like the STS-V suspension and maybe he thought that. However on the V8 they do offer 5 lug wheels that are 18's but still he said it's a different suspension. I also spoke with a mechanic that does very good work and works on my car whenever needed and he said no bigger than 18's and I will be fine.

Does anyone here have a car similar or exact to mine and have put rims on it with the AWD? Is there a huge difference in ride quality and is it possible to do bigger than 18's? I really would like to do alteast 19's but I need some help.

Thanks!

dkozloski
10-08-07, 10:54 PM
The only possible benefit there could be putting to larger rims on your car would be that some people think it enhances the appearance. Every other factor is degraded to one degree or another; braking, handling, ride, acceleration, longevity, strength, cornering power, percentage of unsprung weight, and safety factors are all diminished. It's the engineers nightmare, fashion before function. You'll be driving down the road saying to yourself, "Man! I'm way cool". All the observers that are knowledgable in automotive engineering matters will be saying, "Just another dimbulb".

jjsocrazy
10-09-07, 10:07 AM
The only possible benefit there could be putting to larger rims on your car would be that some people think it enhances the appearance. Every other factor is degraded to one degree or another; braking, handling, ride, acceleration, longevity, strength, cornering power, percentage of unsprung weight, and safety factors are all diminished. It's the engineers nightmare, fashion before function. You'll be driving down the road saying to yourself, "Man! I'm way cool". All the observers that are knowledgable in automotive engineering matters will be saying, "Just another dimbulb".

Do you know of anyone that has put rims on a car like mine or what size would you even recommend putting on even?

Thanks!

dkozloski
10-09-07, 02:07 PM
The car comes from the factory with rims that are optimized by one of the finest engineering teams in the world for best performance and safety.

Spddemon
10-11-07, 12:20 AM
dkozloski, it's not nice to talk about someone else on what they want to do with their car. If you want to keep your car stock that is your decision. As for degraded the cars performance, you can actual gain by putting on different wheel and tire combinations. Granted most wheel/tire combinations do put a strain on the car in other areas, but they can be upgraded to handle it.


jjsocrazy, There are a few different options you can go with, since you didn't say which tire combinations you started with but I am guessing 17's all around. Being that your car does not have a staggered setup you can do 18s,19s, or 20s all around. Some members have even put 22s but run a very low sidewall.

When putting tires on there are different things to take into consideration. I have a stock staggered where the fronts are are 235/45/17. Not sure if yours are 235 or 245 but they are very close in revs per mile which are 768. Any time you upsize your wheel/tires you want to try to keep as close as possible as the revs per mile effects your speedo and odometer.(shorter revs means less miles on the car) when upsizing you will always decrease your size of your sidewall to make up for the rims. as a quick answer to your question I found that 245/35/20s are the closest to stock revs you can get. That tire size will give you a decent sidewall for potholes and pumps and will only increase your speed by .4 mph at 60. If you want to go with a softer ride definitely look at getting 18s as they have a higher side wall or just go with 245/45/20s and have the speedo recalibrated.


18s size would be - 235/45/18
19s size would be - 235/40/19
20s size would be - 245/45/20

As dkozloski said your breaking will degrade but your cornering will be a little improved because of the lower/stiffer side wall. Another suggestion is if you do go with 20s look into getting cross drilled/slotted rotors and upgraded pads to help with the added unsprung weight of the car.

-Joe

jjsocrazy
10-12-07, 10:37 AM
Thank you for your input. Although here is my question, is there a difference with the AWD, I believe no bigger than 18's would be the best.

dkozloski
10-12-07, 11:32 AM
Thank you for your input. Although here is my question, is there a difference with the AWD, I believe no bigger than 18's would be the best.
I put Blizzaks on my '06 V8 AWD STS that are all the same size even though the wheels are staggered widths, and it works fine. As long as the fronts and rears are the same rolling diameter you shouldn't have any trouble with the center differential in the transfer case.

jjsocrazy
10-15-07, 12:20 PM
dkozloski, it's not nice to talk about someone else on what they want to do with their car. If you want to keep your car stock that is your decision. As for degraded the cars performance, you can actual gain by putting on different wheel and tire combinations. Granted most wheel/tire combinations do put a strain on the car in other areas, but they can be upgraded to handle it.


jjsocrazy, There are a few different options you can go with, since you didn't say which tire combinations you started with but I am guessing 17's all around. Being that your car does not have a staggered setup you can do 18s,19s, or 20s all around. Some members have even put 22s but run a very low sidewall.

When putting tires on there are different things to take into consideration. I have a stock staggered where the fronts are are 235/45/17. Not sure if yours are 235 or 245 but they are very close in revs per mile which are 768. Any time you upsize your wheel/tires you want to try to keep as close as possible as the revs per mile effects your speedo and odometer.(shorter revs means less miles on the car) when upsizing you will always decrease your size of your sidewall to make up for the rims. as a quick answer to your question I found that 245/35/20s are the closest to stock revs you can get. That tire size will give you a decent sidewall for potholes and pumps and will only increase your speed by .4 mph at 60. If you want to go with a softer ride definitely look at getting 18s as they have a higher side wall or just go with 245/45/20s and have the speedo recalibrated.


18s size would be - 235/45/18
19s size would be - 235/40/19
20s size would be - 245/45/20

As dkozloski said your breaking will degrade but your cornering will be a little improved because of the lower/stiffer side wall. Another suggestion is if you do go with 20s look into getting cross drilled/slotted rotors and upgraded pads to help with the added unsprung weight of the car.

-Joe

Thank you very much. I might go ahead and stick with 19's all around. I have the 17in wheels right now, sorry I didn't indicate that. Now I wish to get deep dish rims, 19's, and wide tires. I just need help finding good rims, preferable black or chrome. I want 19's because I want to have the look of big rims and still have a good ride, will the 19's still give me a soft ride? BTW, what did you mean by staggered setup?

Thank You!

dkozloski
10-15-07, 04:46 PM
Rims widths in the rear are wider than the rim widths in the front. Stock rear tires are wider than the front tires.

porkfarm
10-15-07, 07:43 PM
The rims are not the same size ? Wow that's good to know.. Any idea what the size diff is ?

jjsocrazy
10-16-07, 09:32 AM
Rims widths in the rear are wider than the rim widths in the front. Stock rear tires are wider than the front tires.

Sounds good! You remind me of my dad when I tell him I am putting rims on. I am looking into getting the 08 STS V8 18in rims though, I can leave them on b/c its a lease and still have a smooth ride.