Start with the sidewall
On the counter at Grattan Quay we start with the tyre that is already on the car. The size is moulded into the sidewall, a code such as 205/55R16 91V. That is the starting point for every quote. Copy it exactly if you are buying in the shop. Do not “go a size up” because a photo looked better unless we have checked load, speed and geometry.
If the tyre is bald, the sticker is gone and you cannot read the door plaque, bring the car in. We will read it in minutes. That is what the workshop enquiry is for. Guessing a plus-size is how arches get rubbed and speedometers lie.
What each number means
Take 205/55R16 91V. Each part of that string means something.
| Mark | Example | What it is |
|---|---|---|
| Width | 205 | Section width in millimetres |
| Profile | 55 | Sidewall height as a % of the width |
| Construction | R | Radial, almost every road tyre we fit |
| Rim | 16 | Wheel diameter in inches |
| Load index | 91 | Maximum load per tyre at the stated pressure |
| Speed rating | V | Maximum speed the tyre is certified for |
Where to find it on an Irish car
Sidewall first. Then the driver’s door shut, the fuel flap, or the handbook. Those plaques are the manufacturer’s approved sizes, including optional plus-sizes. If the plaque lists two rows, the second is often a winter or optional alloy fitment, not a free-for-all.
Vans need the right load index. A 215/65R16C is not the same tyre as a 215/65R16 passenger line even when the first numbers match. Commercial trailer and truck sizes are a Newrath conversation. The duty cycle matters more than the logo.
- Passenger cars and 4x4s: Grattan Quay, 051 873777
- Light truck, trailer, agri: Newrath, 051 857666
- Already know the code? Buy the set in the shop and we fit when you collect.
Load, speed and the EU label
Never drop below the load index on the plaque. A 91-load tyre on an axle that needs 94 is how sidewalls roll. Speed ratings can go up; they should not go down without a documented reason. Irish roads are wet more often than they are dry. The EU tyre label’s wet-grip grade is the letter we look at before rolling resistance.
DOT week/year on the sidewall tells you when the tyre was built. A tyre more than ten years old is due a conversation even if it still has tread. We would rather replace it than sell you another season on a cracked carcass.
Questions we get at the counter
Can I fit a wider tyre than the plaque?
Sometimes, on the right wheel with the right offset and load rating. We check that on the car at Grattan Quay. Buying a wider size from a photo is how speedos and arches go wrong.
The two axles have different sizes. Is that normal?
On some performance cars, yes. Quote both sizes. Do not match them up without asking. Mixed axles are a workshop job.
I only need two tyres. Front or rear?
New rubber goes on the rear unless we have a reason not to. That is the safer axle if you lose grip in the wet. Tell us what is already on the car.
Shop or send an enquiry
If you already know the size or the wheel, pay in the shop. If you want us to read it off the car, make an enquiry. We call you back.