Tyre Size Calculator

[KiwiTT]

Use this (http://www.miata.net/garage/tirecalc.html) to see if the new tyre is the right size.

VR-4 Original = 225/50 R16

If travelling @ 60 mph with the same width tyres and increasing diameters

225/45 R17 = 0.5% too slow = 60.3 mph
225/40 R18 = 0.9% too slow = 60.6 mph
225/35 R19 = 1.4% too slow = 60.8 mph
225/30 R20 = 1.8% too slow = 61.1 mph

[jerryd_33]

looking to buy a VR-4 as soon as i get my MERCEDES C230 KOMPRESSOR sold , but i want to know is the brake disc diameter for the standard front and rear of the VR-4 please and if they are good or weather i would need to up grade them for better ones ?

[KiwiTT]

... to up grade them for better ones ?

Depends on how hard you drive. If you are like me and use the engine breaking more. Then you won't need to.

However, as this is a Sports-Sedan, you are not doing it justice, if you don't push it occassionally. Search on Brakes and you'll find some have put brembo's on. I will probably do this, when I do my brake upgrade.

[zedy1]

Use this (http://www.miata.net/garage/tirecalc.html) to see if the new tyre is the right size.

VR-4 Original = 225/50 R16

If travelling @ 60 mph with the same width tyres and increasing diameters

225/45 R17 = 0.5% too slow = 60.3 mph
225/40 R18 = 0.9% too slow = 60.6 mph
225/35 R19 = 1.4% too slow = 60.8 mph
225/30 R20 = 1.8% too slow = 61.1 mph


does that mean my 0-60 second times are 0.6 seconds quicker?

[KiwiTT]

does that mean my 0-60 second times are 0.6 seconds quicker?

About 1% for your 225/40 R18. This means you really reach 60mph at 5.03 not 5.08 (i.e. you can subtract 5/100ths of a second, not 6/10ths)

Also, while your 1/4 mile times and speeds will be accurate as they are externally measured.