OEM 17" Tire Size Choices
08-09-2007 | 07:09 AM
#1
OEM 17" Tire Size Choices
I've done a lot of reading and learning the past few days on the options. I narrowed it down to two and I want to see if I missed out on anything. I also wanted to see which would work best for me. So here goes.
OEM 17" Wheels are tires
17x7.5 F 225/50 Circumference: 81.21 in Diameter: 25.85 in
17x8.0 R 235/50 Circumference: 82.46 in Diameter: 26.25 in
Difference of: Circ: -1.25 in (-1.51%) Diam: -0.4 in
Here are the choices I was presented with.
The closest to stock is
245/45 Circumference: 80.67 in Diameter: 25.68 in
255/45 Circumference: 81.77 in Diameter: 26.03 in
Difference of: Circ: -1.1 in (-1.35%) Diameter: -0.35 in
I could also go
235/45 Circumference: 79.54 in Diameter: 25.32 in
245/45 Circumference: 80.67 in Diameter: 25.68 in
Difference of: Circ: -1.13 in (-1.40%) Diameter: -0.36 in
Clearly both sets of tires will adhere to the front/rear speed differences based on their difference in circumference since as stated many times we have about +-3% to work with.
The one labeled closest to stock has tires that will not upset my speedo as much, since their circumferences are closer to the stock ones.
I thought this was an easy decision because I like how the one closest to stock matches up. However, I have been told by two separate tire guys that 255mm is too large for 8" wide rim. The tires I'm looking at say their recommended rim size 8-9.5 so I am right on the bottom edge. Same goes for the 245mm on a 7.5" rim, recommended is 7.5-9.
At this point my knowledge base runs out.
So my questions are, what is the significance of the diameter differences, if any?
Should I really be concerned with the rim width being the minimum recommended?
The car is my daily driver, but I do maybe 1-2 HPDE type events a year.
Thanks,
Steve
OEM 17" Wheels are tires
17x7.5 F 225/50 Circumference: 81.21 in Diameter: 25.85 in
17x8.0 R 235/50 Circumference: 82.46 in Diameter: 26.25 in
Difference of: Circ: -1.25 in (-1.51%) Diam: -0.4 in
Here are the choices I was presented with.
The closest to stock is
245/45 Circumference: 80.67 in Diameter: 25.68 in
255/45 Circumference: 81.77 in Diameter: 26.03 in
Difference of: Circ: -1.1 in (-1.35%) Diameter: -0.35 in
I could also go
235/45 Circumference: 79.54 in Diameter: 25.32 in
245/45 Circumference: 80.67 in Diameter: 25.68 in
Difference of: Circ: -1.13 in (-1.40%) Diameter: -0.36 in
Clearly both sets of tires will adhere to the front/rear speed differences based on their difference in circumference since as stated many times we have about +-3% to work with.
The one labeled closest to stock has tires that will not upset my speedo as much, since their circumferences are closer to the stock ones.
I thought this was an easy decision because I like how the one closest to stock matches up. However, I have been told by two separate tire guys that 255mm is too large for 8" wide rim. The tires I'm looking at say their recommended rim size 8-9.5 so I am right on the bottom edge. Same goes for the 245mm on a 7.5" rim, recommended is 7.5-9.
At this point my knowledge base runs out.
So my questions are, what is the significance of the diameter differences, if any?
Should I really be concerned with the rim width being the minimum recommended?
The car is my daily driver, but I do maybe 1-2 HPDE type events a year.
Thanks,
Steve
08-09-2007 | 04:56 PM
#2
I've used 235/45 and 245/45 on stock wheels. It mounted up fine and grip did increase, but the sidewalls were very mushy or loose. I stepped up the wheel size to 8.5" wide front & rear and that little bit of stretch really stiffened things up. Now, I am extremely pleased with those tire sizes.
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