TDAE in Tire Compounding: How Process Oil Choice Moves Wet Grip and Rolling Resistance

Procurement teams tend to evaluate process oil on price, specification and availability. Tire technologists evaluate it on something else entirely: where it puts the compound on a curve. Understanding that curve explains why a tread formulation specifies TDAE rather than a cheaper alternative — and why substituting oils is never a like-for-like swap. If you are new to the grade itself, start with what TDAE is.

The magic triangle

Tire development is governed by three properties that resist simultaneous improvement: wet grip, rolling resistance, and wear resistance. The industry calls this the magic triangle, and the reason it is hard is that the first two are physically linked. Both arise from hysteresis — energy lost as the rubber deforms and recovers — so a change that increases one usually increases the other.

The trick the industry uses is that the two matter at different temperatures and frequencies.

How tan δ is read

Dynamic mechanical analysis produces a tan δ curve across temperature, and the industry reads two points on it as proxies for real-world performance:

The logic behind each: wet braking is a high-frequency, low-temperature event — the tread deforms rapidly against road texture, and you want high hysteresis there, because that energy loss is what generates grip. Rolling, by contrast, happens at a running tread temperature typically in the 50–70 °C range, and every unit of hysteresis at that temperature is fuel burned. So you want the loss peak positioned to be high at 0 °C and low at 60 °C.

That positioning is largely determined by the compound's glass transition temperature — and process oil is one of the main levers a formulator has to move it.

Where process oil comes in

A process oil acts as a plasticiser. Its own Tg blends into the compound, shifting the whole tan δ curve along the temperature axis. Move the curve up in temperature and the 0 °C reading rises — better wet grip — but the 60 °C reading tends to rise too, worsening rolling resistance. Move it down and the reverse happens.

This is why TDAE became the tread standard after the DAE restriction. Among the compliant oils, its glass transition temperature is the highest — roughly −44 to −50 °C against MES at −57 to −63 °C. That relatively high Tg positions the curve where wet grip benefits most, which is exactly what a performance tread compound is sold on. For the full grade-by-grade picture, see how TDAE compares with MES, RAE and naphthenic grades.

It is also why switching from TDAE to MES is not a neutral substitution. MES pulls compound Tg down, improving cold flexibility and rolling resistance, at the cost of the 0 °C tan δ that determines wet braking. For a winter compound that trade is often correct. For a summer performance tread it usually is not.

One subtlety worth knowing: in silica-filled SSBR compounds, TDAE's Tg sits close to the polymer's own, which is part of why adding TDAE within normal loadings produces relatively little Tg shift compared with oils further from the polymer's Tg. The oil is doing its plasticising work without dragging the compound off its designed position on the curve — a quieter advantage than the headline aromaticity, and one reason formulators are reluctant to move away from it.

Loading levels

Tread compounds typically run process oil in the region of 30–40 phr, with 37.5 phr appearing frequently as a reference loading in published tread studies. Loadings much above that range become impractical for tread — mechanical properties deteriorate to the point where the compound is no longer suitable regardless of what the tan δ numbers say.

Within the workable range, increasing oil loading softens the compound, aids filler dispersion and processing, and shifts the balance — which is why oil level and oil type are tuned together rather than separately.

What this means commercially

Three practical consequences for anyone buying or specifying process oil.

Batch consistency matters more than headline price. A compound is designed around a specific position on the tan δ curve. An oil parcel that drifts on aromaticity or viscosity from batch to batch moves that position, and the tire fails its own performance targets. This is why tire manufacturers qualify oil suppliers rather than buying spot on price.

Substitution requires reformulation, not just a purchase order. Replacing TDAE with MES, RAE or a bio-based alternative changes compound Tg, cure behaviour and filler interaction. Published work on TDAE replacements consistently shows this — even blends specifically designed to match TDAE's Tg require deliberate formulation work to get there.

The pressure on TDAE is coming from resins and bio-based plasticisers, not from other mineral oils. Hydrocarbon resins and modified bio-oils are the active research frontier for tread plasticisers, driven by sustainability targets. For the foreseeable term, though, TDAE remains the reference against which those alternatives are benchmarked — which tells you where the performance standard still sits.

The short version

Process oil is not a filler or a cost line. It is a formulation lever that moves the compound along the temperature axis, and TDAE occupies the position that tread compounds were designed around. That is why it commands a premium over less aromatic alternatives, and why buying it on specification consistency rather than headline price is the rational approach.

Frequently Asked Questions

Sanyang Petroleum supplies the SANYANG TDAE Series (grades T100–T1200) to tire manufacturers, retreaders and rubber goods producers across Southeast Asia, South Asia and the Middle East, with batch-specific COAs and EN 16143:2013 PAH analysis as standard. Contact info@sanyangpetroleum.com or submit an RFQ.