There are a number of calculators out there.
This one allows for comparison say from your OEM size to whatever size you'd consider changing to.
If you're looking for a "car" tire and the aspect ratios available don't match the OEM you can determine what the new diameter, circumference, speedometer error, etc will be.
Most importantly, does it fit in the fenders.
Just beware, those comparison charts rarely show any SPECIFIC size comparisons between different Brands, types of tires, tread patterns etc - they usually only show a comparison between the NOMINAL sizes that are written on the sidewalls, and the ACTUAL physical size of any tire may be significantly different due to differences in the way each manufacturer or even each different tire type may be measured!! Some use the pre-tread tire carcass to determine the closest nominal size; some include the tread base layers but not the tread depth; others use the size of the final production tire including the full tread depth - but none will tell you that up front!!
So while these calculators/comparison tools are a good starting guide when choosing tires, you still really need to compare the ACTUAL manufacturers specs of any tires you are considering, usually the Rolling Radius or Diameter, or the Revs per Mile will allow a direct comparison But even then, if you find two different tires that have exactly the same dimensions, chances are that manufacturer took the lazy way out & only provided the Nominal size details instead of their tire's actual physical dimensions - different tires are very rarely exactly the same size as any other/brand of tire/tread pattern.
And just by the way, the OE Spec Kendas on our Spyders/Rykers have a relatively small diameter tire with that Nominal sidewall size, but they are relatively wide for a tire wearing that Nominal size. Still, for the 2013 & on Spyders, most tires in 50, 55, 60, or 65 profiles between 205/65R15 up to 225/60R15 will fit on our Spyder rear rims & work pretty well; while most similarly profiled tires between 155/65R15 & 175/60R15 will fit up front, altho some Owners have found/managed to squeeze 185/50 or 55R15's under the fenders, some with spacers - but BE WARNED, if you increase/decrease the rolling dia/revs per mile of your tires up front, you should at least aim for a reasonably similar increase/decrease in the rolling dia/revs per mile on the rear. Changing the proportional rolling dia too much between your front and rear tires can make your Spyder feel a little unstable, even if the Nanny does usually intervene before it gets too ugly!!
But again, please don't solely rely on those tire size comparison apps &/or charts; they usually only compare NOMINAL sidewall sizes & not the ACTUAL physical sizes of specific brands &/or types of tires, and they are really only intended as a GUIDE to allow you to start your tire selection process - you still need to compare the ACTUAL physical dimensions of any replacement tire to a tire that's know to fit, or you risk being embarrassed when it comes to installation time!
I will be ordering the VREDESTEIN QUATRAC 5 tires this week to replace the plastic Kendras. Can anyone provide the best sizes for front-back proportions? I.e., if I go with rear 205/65r-15, what should the fronts be?
I will be ordering the VREDESTEIN QUATRAC 5 tires this week to replace the plastic Kendras. Can anyone provide the best sizes for front-back proportions? I.e., if I go with rear 205/65r-15, what should the fronts be?
Front 165/60r15 front Vredestein
Rear 225/50r15 rear Kumo E
I put this combo on my 2019F3L 2 weeks ago....
Couldn’t be happier.
175/55R15 is another common one that has been posted too on here but runs close to the newer fender design. Not really sure which is better the 165/60R15 or the 175/55R15. Been watching this same conversation for about 6 months now. I will need new fronts in the 4000 miles or so. I really like the tread of the Quatrac5. I will be getting one or other depending on how the majority go over the winter. I'm riding a 2017 RT limited with Altimax RT 215/60 R15 on the rear with about 8000 miles on the rear.
“Born to Ride......Ride to Live....MOATER ON !
“Current ride: 2017 RT Limited”
I will be ordering the VREDESTEIN QUATRAC 5 tires this week to replace the plastic Kendras. Can anyone provide the best sizes for front-back proportions? I.e., if I go with rear 205/65r-15, what should the fronts be?
Can't say what is <best>, but I went with 205/65-15 on the rear and 175/55-15 on the front.
No spacers used on the front fenders, but let's just say the fenders are FULL.
I will be ordering the VREDESTEIN QUATRAC 5 tires this week to replace the plastic Kendras. Can anyone provide the best sizes for front-back proportions? I.e., if I go with rear 205/65r-15, what should the fronts be?
I have the 165/60-15 Q-5's ..... the difference in lateral traction, would be too small to measure accurately. Plus the fact that the VSS will kick in long before you actually lose any traction. ..... Good choice .... Mike
youve already got significant spedo error! a 215 60 15 tire almost gets it right, and it is a common size which means you can get a common brand you have heard of!
Can some one tell me if the Altimax 225x60x15 will fit and work well on a 2015 F3-S. It now has the original 225x55x15 on it? I like the wide profile of the 225. thank you
Just beware, those comparison charts rarely show any SPECIFIC size comparisons between different Brands, types of tires, tread patterns etc - they usually only show a comparison between the NOMINAL sizes that are written on the sidewalls, and the ACTUAL physical size of any tire may be significantly different due to differences in the way each manufacturer or even each different tire type may be measured!! Some use the pre-tread tire carcass to determine the closest nominal size; some include the tread base layers but not the tread depth; others use the size of the final production tire including the full tread depth - but none will tell you that up front!!
So while these calculators/comparison tools are a good starting guide when choosing tires, you still really need to compare the ACTUAL manufacturers specs of any tires you are considering, usually the Rolling Radius or Diameter, or the Revs per Mile will allow a direct comparison But even then, if you find two different tires that have exactly the same dimensions, chances are that manufacturer took the lazy way out & only provided the Nominal size details instead of their tire's actual physical dimensions - different tires are very rarely exactly the same size as any other/brand of tire/tread pattern.
And just by the way, the OE Spec Kendas on our Spyders/Rykers have a relatively small diameter tire with that Nominal sidewall size, but they are relatively wide for a tire wearing that Nominal size. Still, for the 2013 & on Spyders, most tires in 50, 55, 60, or 65 profiles between 205/65R15 up to 225/60R15 will fit on our Spyder rear rims & work pretty well; while most similarly profiled tires between 155/65R15 & 175/60R15 will fit up front, altho some Owners have found/managed to squeeze 185/50 or 55R15's under the fenders, some with spacers - but BE WARNED, if you increase/decrease the rolling dia/revs per mile of your tires up front, you should at least aim for a reasonably similar increase/decrease in the rolling dia/revs per mile on the rear. Changing the proportional rolling dia too much between your front and rear tires can make your Spyder feel a little unstable, even if the Nanny does usually intervene before it gets too ugly!!
But again, please don't solely rely on those tire size comparison apps &/or charts; they usually only compare NOMINAL sidewall sizes & not the ACTUAL physical sizes of specific brands &/or types of tires, and they are really only intended as a GUIDE to allow you to start your tire selection process - you still need to compare the ACTUAL physical dimensions of any replacement tire to a tire that's know to fit, or you risk being embarrassed when it comes to installation time!
Good Luck!
With all of this considered, I prefer to do my own calculations in an Excel spreadsheet where I can look at multiple sizes all at once instead of just two at a time. This can be as few as two for comparison or as many as you want to copy down with the rows from the first and second ones.
Here you can see three size choices as it normally appears in Excel. I then broke it into segments in the second grouping with the last grouping showing the formulas used. I did not do a revs/mile formula as I was not concerned about that at the time. All I was really after was getting an approximate size that would deliver a fairly accurate speedometer correction based on the error I was seeing when compared to GPS readings.
Before anyone points out GPS readings are not accurate, they are dependent on where and how they are taken. Here in the Tx Panhandle, you can find roads that are almost dead flat and straight for miles & miles. That allows for very accurate readings, especially on clear days where your GPS is showing 5 satellites.
I chose the 205/65 as the change in circumference (%cir) was pretty close to the error recorded from GPS. After mounting and test riding with the same two GPS units as before, my results were astounding. At 75mph indicated both GPS were showing and actual speed of 74.5
Bear in mind, the manufacturing variances Peter pointed out though. I got lucky with my choice in achieving an almost spot on speedometer.
Can some one tell me if the Altimax 225x60x15 will fit and work well on a 2015 F3-S. It now has the original 225x55x15 on it? I like the wide profile of the 225. thank you
Yes, yes, yes, ..... and this size will correct your speedometer to almost perfect. .... the OEM size Kenda, reads about 3 mph fast. ..... Mike
With all of this considered, I prefer to do my own calculations in an Excel spreadsheet where I can look at multiple sizes all at once instead of just two at a time. This can be as few as two for comparison or as many as you want to copy down with the rows from the first and second ones.
Here you can see three size choices as it normally appears in Excel. I then broke it into segments in the second grouping with the last grouping showing the formulas used. I did not do a revs/mile formula as I was not concerned about that at the time. All I was really after was getting an approximate size that would deliver a fairly accurate speedometer correction based on the error I was seeing when compared to GPS readings.
Before anyone points out GPS readings are not accurate, they are dependent on where and how they are taken. Here in the Tx Panhandle, you can find roads that are almost dead flat and straight for miles & miles. That allows for very accurate readings, especially on clear days where your GPS is showing 5 satellites.
I chose the 205/65 as the change in circumference (%cir) was pretty close to the error recorded from GPS. After mounting and test riding with the same two GPS units as before, my results were astounding. At 75mph indicated both GPS were showing and actual speed of 74.5
Bear in mind, the manufacturing variances Peter pointed out though. I got lucky with my choice in achieving an almost spot on speedometer.
The chart Only gives a " MATHMATICAL " size. ..... Actual tire size will different depending on which manufacturer made that tire. ..... Mike
This makes for a great discussion subject. When it comes time, I will leave the suggestions to my mechanic. Here either Spyderpops or Lamonster. I am lucky to be close to both places.
Currently Owned: 2019 F3 Limited, 2020 F3 Limited: SOLD BOTH LIMITEDS in October of 2023.
Tire Size Comparison Calculator
Reply With Quote
But even then, if you find two different tires that have exactly the same dimensions, chances are that manufacturer took the lazy way out & only provided the Nominal size details instead of their tire's actual physical dimensions - different tires are very rarely exactly the same size as any other/brand of tire/tread pattern. 
Still, for the 2013 & on Spyders, most tires in 50, 55, 60, or 65 profiles between 205/65R15 up to 225/60R15 will fit on our Spyder rear rims & work pretty well; while most similarly profiled tires between 155/65R15 & 175/60R15 will fit up front, altho some Owners have found/managed to squeeze 185/50 or 55R15's under the fenders, some with spacers - but BE WARNED, if you increase/decrease the rolling dia/revs per mile of your tires up front, you should at least aim for a reasonably similar increase/decrease in the rolling dia/revs per mile on the rear. Changing the proportional rolling dia too much between your front and rear tires can make your Spyder feel a little unstable, even if the Nanny does usually intervene before it gets too ugly!! 
Originally Posted by RayBJ
!
