bigbo
Aurora Newbie
Posts: 11
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Post by bigbo on Aug 27, 2016 15:34:58 GMT -6
Is that the "largest" tire I could put on my Aurora 2001? Im not good at tire sizing, I like large tire, but not big 20" mag, 17" is alright ahah
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Post by sall on Aug 27, 2016 15:58:12 GMT -6
The diameter is not the problem. It is the width. You may able to get 245s on the factory 7.5" wheel but I doubt it. I run 255/35/20s on 20x8.5" +32mm offset.
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bigbo
Aurora Newbie
Posts: 11
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Post by bigbo on Aug 27, 2016 16:47:58 GMT -6
Most of the large tires are for 19,20s, thats why Im asking if there's a middle between large and 17" ahah!
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235/55R17
Aug 28, 2016 0:58:05 GMT -6
via mobile
Post by YellowBeard on Aug 28, 2016 0:58:05 GMT -6
I'm running 245's on my orange juicers. Haven't had any problems and they look awesome. They are Ultra HP A/S and a tiny tiny bit under the load rating (98 vs. 100). Speedo is off by only 2 mph and they dropped the car about an inch or more. Steering response is lightning quick. Plus boy do they grip!
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Post by sall on Aug 28, 2016 12:03:46 GMT -6
The width did not drop your car the sidewall height did. According to the calc with 245/50-16 tires speedo would read ~3mph slower at 60mph. The 245/55-16 is about as close as you can get on classic/3.5L 2G in 245 width and 1mph slower on speedo at 60mph. My wheel/tire setup is 0.2mph slower on the speedo at at 60mph.
Anyways OP is you have the 2G 4.0, the calc I was using stated a 255/50-17 would fit on the OEM 7.5" rim. That would give you 0.2mph slower at 60mph. The calc has proven more reliable to me than the chart I pulled stating 245s might fit on the 7.5" rim haha. I had great luck with when configuring my whee/tire setup and getting the offset just right.
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Post by YellowBeard on Aug 29, 2016 1:29:42 GMT -6
The width did not drop your car the sidewall height did. You're right. I should have said, tires dropped the car instead of they. I agree the way it reads can be a bit misleading.
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XJSman89
Administrator
Posts: 6,309
Staff Member
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Post by XJSman89 on Aug 30, 2016 20:51:00 GMT -6
The easiest way to understand tire sizes:
The first number (235) is the tire width in millimeters. The bigger the number, the wider the tire. There is a limit to what you can fit on your wheel, however, being a 7.5" wide wheel.
The second number (55) is an aspect ratio, saying that the sidewall is 55% of the width of the tire. Even though they might both be 55s, the sidewall on a 235/55 would be smaller than the sidewall on a 245/55 because the second has a larger diameter and 55% of a larger number is, by necessity, also a larger number.
The third letter/number(R17) is "R" for "radial" (all modern tires are radials) and "17" is your wheel diameter. Whatever the "R" number on your current tire is, your new tire will also need to be, unless you plan on getting larger wheels. There's no getting around this. You can't put a 18" tire on a 17" wheel.
I would google a tire size calculator, there are many that can help you compare tire sizes and pick the right one. With one of those you can easily get a wider tire that ends up having a very similar sidewall just by playing with the numbers. That way you can have the grip of a larger tire with similar ride quality (and speedo readings) of your current tire. I used one extensively when researching tire sizes for my 370Z, and ended up finding one in the perfect size that is wider and shorter than stock in a better tire than was available in the OEM size. Sometimes OEM isn't the answer!
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235/55R17
Aug 31, 2016 0:08:41 GMT -6
via mobile
Post by YellowBeard on Aug 31, 2016 0:08:41 GMT -6
Got this calculation off TireRack.com many many moons ago:
First Gen Stock Tire Size (numbers have been paired down to 3 decimal places)
Tire width Divided by 25.4 (235 ÷ 25.4 = 9.252)
Take the number above an divide by 2 (9.252 ÷ 2 = 4.626)
Take the number above and times it by sidewall height (4.626 × 0.65 = 3.007)
Take the number above and times it by 2 (3.007 × 2 = 6.014)
Lastly add the number above to the diameter (6.014 + 16 = 22.014)
The first gen Aurora's tire "size" for calculating a different tire is 22. When choosing a new tire you do not want to go bigger or smaller than 1 point from that number. Truthfully you want to get as close to 22 as possible in order to retain the stock height. If that is your desire.
If we plug the numbers in for the 235 55 r17, we come up with 22.089. With this tire you car should "sit" a little higher than stock because it is higher than 22.014. That's fine though because you are within that 1 point up/down range. There shouldn't be any problems with that tire as long as the rim is the same width as the stock one. Otherwise you might need spacers.
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