normcloutier Posted July 11, 2012 Report Share Posted July 11, 2012 I have a 13 Edge SEL AWD that came from factory with 18" wheels. The 20" chrome 5 spoke fork looking ones that I wanted were only available on the Limited so I had the dealer swap them out after arrival. From factory,18" wheels have a 3.16 gear ratio while 20" have 3.39. Because mine were not factory, I have 20" wheels with a 3.16 gear ratio. I had my edge in for some touch-ups today and was given a Limited to drive and there was a noticeable difference in zip on the Limited. The Limited seemed more responsive and quicker. I'm not sure if it's a downshifting issue or simply wheel size. I found an online tire comparison tool and when I input the info on the 2 different tire sizes, the difference in circumference was minimal. My speedometer is bang on within 1 KM/H at 110 KM/H with the 20's so either the factory wheels would have made the speedometer very inaccurate or something else is afoot. Has anyone else experienced this by switching tire size? Since my 20's were on the vehicle when I took delivery, I had nothing to compare it to. Downshifting when pressing on the accelerator in the Limited seemed to occur way easier than my SEL. Sometimes I feel like I nearly have to floor my SEL before it downshifts. Quote Link to comment Share on other sites More sharing options...
akirby Posted July 11, 2012 Report Share Posted July 11, 2012 The difference is not the size - as you found out the tire circumference is virtually the same. The difference is in the weight. Your wheels are heavier and it takes more oomph to get them turning. I don't think the difference would be worth the effort to swap it out. Quote Link to comment Share on other sites More sharing options...
normcloutier Posted July 11, 2012 Author Report Share Posted July 11, 2012 Hmm. I appreciate your response. Not sure that would be it. The Limited had a Vista roof and that in itself would be much heavier than the difference between the weight of the 20's over the 18's. The Limited would be heavier overall so the result should have been the opposite. I wonder if the Limited was just FWD. I'll have to find out. Quote Link to comment Share on other sites More sharing options...
normcloutier Posted July 11, 2012 Author Report Share Posted July 11, 2012 The Limited was AWD so that's not it. It only had 40km on it where my SEL has 1600. I have driven pretty conservatively during this break in period and in fact only brought myself to flooring it about a week ago. Has the adaptive transmission adjusting itself to my wimpy driving? I read a few posts about the tranny and am still unclear if it adjusts itself to your driving style or simply provides the same shift feel over the life of the vehicle. Quote Link to comment Share on other sites More sharing options...
akirby Posted July 12, 2012 Report Share Posted July 12, 2012 It's not the overall weight. It's the weight of the wheels and getting the wheels turning from a dead stop. Heavier wheels require more hp. So yes, that is it. 1 Quote Link to comment Share on other sites More sharing options...
normcloutier Posted July 12, 2012 Author Report Share Posted July 12, 2012 The Limited I drove today has the exact same wheels as my SEL. Quote Link to comment Share on other sites More sharing options...
Waldo Posted July 12, 2012 Report Share Posted July 12, 2012 It's the final drive ratio. A 3.39 final drive is intended specifically to make the car feel like it has more zip. The downside is that it burns more fuel. Quote Link to comment Share on other sites More sharing options...
normcloutier Posted July 12, 2012 Author Report Share Posted July 12, 2012 So the ratio has nothing to do with the wheel size but rather more with performance? If that is the case, then that would explain why my speedometer is accurate even with the larger wheels. If the higher ratio means less fuel economy, then I'm glad I have 3.18. I am only getting 400 km per tank in the city. With a light foot too. Thanks to all. Quote Link to comment Share on other sites More sharing options...
akirby Posted July 12, 2012 Report Share Posted July 12, 2012 So the ratio has nothing to do with the wheel size but rather more with performance? If that is the case, then that would explain why my speedometer is accurate even with the larger wheels. If the higher ratio means less fuel economy, then I'm glad I have 3.18. I am only getting 400 km per tank in the city. With a light foot too. Thanks to all. Ok, let's try this again. You're confusing different things. The speedometer is based on the circumference of the TIRE, not the wheel. 18s and 20s have the same size TIRE therefore the speedo is the same. It has nothing to do with the gear ratios since it's driven off the ABS wheel speed sensors and not off the transmission like older cars. Bigger wheels are heavier and are therefore slower from a stop to get going. They compensate for that with a numerically higher gear ratio. So the end result from the factory is that the 18s and 20s feel the same because of the change in ratios. Since you have the 20s with the gear ratio of the 18s it feels slower. If you had gotten the 20s from the factory with the higher ratio it would feel quicker. Capiche? Quote Link to comment Share on other sites More sharing options...
normcloutier Posted July 13, 2012 Author Report Share Posted July 13, 2012 Si Quote Link to comment Share on other sites More sharing options...
Aurora watcher Posted November 2 Report Share Posted November 2 A.kirby is out to lunch. Capiche? It is all to do with the rear end ratio. The lower the ratio, the more horsepower it will take to match the acceleration of a vehicle with a higher numbered ratio. Police interceptors are likely to have a 2.53 ratio and a Camero is likely to have 3.80 or 4.11 rear end ratios. The Camero will leave the interceptor behind at the start but can never beat it for top end speed. At highway speeds your lower ratio would have your engine running at a slightly lower rpm which translates into better fuel mileage, but sacrifices get up and go. If you live live in really hilly terrain and have to pull a lot of hills you would want a higher numbered ratio as that allows for better performance in the hills. Higher ratios can be used by car makers to give better acceleration from less horsepower engines because it takes less horsepower to make the vehicle accelerate quicker like it felt in the Limited you drove. ABSOLUTELY NOTHING TO DO WITH HEAVIER WHEELS.... Dave 1 Quote Link to comment Share on other sites More sharing options...
Cerberus Posted November 2 Report Share Posted November 2 6 hours ago, Aurora watcher said: A.kirby is out to lunch. Capiche? It is all to do with the rear end ratio. The lower the ratio, the more horsepower it will take to match the acceleration of a vehicle with a higher numbered ratio. Police interceptors are likely to have a 2.53 ratio and a Camero is likely to have 3.80 or 4.11 rear end ratios. The Camero will leave the interceptor behind at the start but can never beat it for top end speed. At highway speeds your lower ratio would have your engine running at a slightly lower rpm which translates into better fuel mileage, but sacrifices get up and go. If you live live in really hilly terrain and have to pull a lot of hills you would want a higher numbered ratio as that allows for better performance in the hills. Higher ratios can be used by car makers to give better acceleration from less horsepower engines because it takes less horsepower to make the vehicle accelerate quicker like it felt in the Limited you drove. ABSOLUTELY NOTHING TO DO WITH HEAVIER WHEELS.... Dave bold strategy.. You revive a 12 year old thread by insulting a moderator... while admittedly correcting a false statement. but to be fair you didn't address the elephant in the room, the transmission operation being described as operating in a somewhat lazy mode. being slow to downshift does tend to be a fuel saving tactic, and not good for performance. these shifting algorithms are being reworked all the time and adaptive self adjustments make it even harder to compare apples to apples.. nevermind the final drive ratios being different, and the shift programming likely being different as well And this all assumes the engines of both vehicles were in identical condition with identical conditions. Heck, a cool day can make most engines perform better.. bottom line, its hard to pinpoint one single cause, but yes, if the final drive ratios are different, the numerically higher one will tend to have a lot more acceleration with everything else being equal Quote Link to comment Share on other sites More sharing options...
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