Tyre Upsize Calculator with the 3% formula helps you choose a new tyre size by considering 3% as the maximum allowed change in diameter for the new tyre. The tool lets you know your vehicle’s diameter, performance, and safety while upgrading your tyre. Just plug in your numbers and see your options, safety verdicts, and comparisons—all in a single click.
3% Tyre Upsizing Calculator
Although many Indian drivers use the 3% rule, we recommend you to use our tyre upgrade calculator with recommended 2.5% formula for better safety compliance.
What is the 3 Percent Rule for Tyre Size?
The 3% rule for tyre upgrade is:
Never increase or decrease your tyre’s overall diameter by more than 3% compared to the original OEM tyre sizes.
Most experts, including those at MRF and Bridgestone, recommend keeping changes within 2%. But a little flexibility is sometimes needed to get a higher ground clearance and looks. So, the 3% is the absolute ceiling. It balances real-world practicality with technical safety.
What Happens If You go beyond 3%?
If you go beyond the 3% limit in diameter, you will face these three issues:
- Too big: Your speedometer says 60 km/h, but you’re actually cruising at 65+. Not good for traffic fines or braking safety!
- Too small: Lower ground clearance—watch out for those Bangalore speed breakers and Kerala potholes.
- Beyond 3%: Your ABS, traction control, and even warranty may not work as intended.
How the Tyre Upsize Calculation with 3% Rule Works
It’s super simple:
- Enter your current tyre’s width, aspect ratio, and rim diameter.
- Enter your new/proposed tyre size.
- Hit Calculate!
- Instantly see:
- Percentage difference in diameter
- Safety verdict (Safe / Caution / Not Allowed)
- Side-by-side specs and more
When Is It Okay to Go Up to 3%?
Some Indian cars and SUVs like Hyundai Creta, Kia Seltos etc. are built tough, with ample wheel arch clearance. If your manufacturer allows it (always check the manual), and your upsize falls within the 3% “caution” zone, you’re generally good. But remember that you should regularly check for rubbing, odd noises, and tyre wear.
Never ever go above 3%, unless you love surprise mechanic visits!
Frequently Asked Questions
Is it really safe to upsize by up to 3%?
Usually, yes, but always check the wheel well clearance and local RTO rules. Stay below 2% for best results, and only go up to 3% if you must.
How will a 3 per cent upsize change my speedometer?
If your speedometer reads 60 km/h, with a 3% upsize, you’re actually moving about 61.8 km/h. Use our calculator for the exact figure.
Will a 3% upsize affect my mileage?
Yes, a small drop in fuel efficiency is expected—often 1–3%.
Do I need to change my rims for a 3% upsize?
Not always. Sometimes you can upsize width or aspect ratio while keeping your original rim. The calculator helps you check all combos.